diff --git a/src/Ausgabenverwaltung.cpp b/src/Ausgabenverwaltung.cpp
index 4597085..2ba124f 100644
--- a/src/Ausgabenverwaltung.cpp
+++ b/src/Ausgabenverwaltung.cpp
@@ -11,104 +11,104 @@ using namespace std;
 class invoice
 {
 private:
-	int number_ = 0;
-	double amount_;
-	unsigned short month_ = 0;
-	int category_ = 0;
+    int number_ = 0;
+    double amount_;
+    unsigned short month_ = 0;
+    int category_ = 0;
 public:
-	/**
-	 * \brief collection of categories
-	 */
-	static const char* categories[];
-	/**
-	 * \brief collection of months
-	 */
-	static const char* months[];
+    /**
+     * \brief collection of categories
+     */
+    static const char* categories[];
+    /**
+     * \brief collection of months
+     */
+    static const char* months[];
 
-	/**
-	 * \brief Creates a new instance of invoice
-	 */
-	invoice(const int number, const double amount, const unsigned short month, const int category) : number_(number),
-	                                                                                                 amount_(amount),
-	                                                                                                 month_(month),
-	                                                                                                 category_(category)
-	{
-	}
+    /**
+     * \brief Creates a new instance of invoice
+     */
+    invoice(const int number, const double amount, const unsigned short month, const int category) : number_(number),
+        amount_(amount),
+        month_(month),
+        category_(category)
+    {
+    }
 
-	/**
-	 * \brief Get number of invoice.
-	 * \return current number
-	 */
-	int get_number() const
-	{
-		return number_;
-	}
+    /**
+     * \brief Get number of invoice.
+     * \return current number
+     */
+    int get_number() const
+    {
+        return number_;
+    }
 
-	/**
-	 * \brief get month of invoice
-	 * \return month as index
-	 */
-	unsigned short get_month() const
-	{
-		return month_;
-	}
+    /**
+     * \brief get month of invoice
+     * \return month as index
+     */
+    unsigned short get_month() const
+    {
+        return month_;
+    }
 
-	/**
-	 * \brief get category of invoice
-	 * \return category as index
-	 */
-	int get_category() const
-	{
-		return category_;
-	}
+    /**
+     * \brief get category of invoice
+     * \return category as index
+     */
+    int get_category() const
+    {
+        return category_;
+    }
 
-	/**
-	 * \brief get amount of invoice
-	 * \return amount in euro
-	 */
-	double get_amount() const
-	{
-		return amount_;
-	}
+    /**
+     * \brief get amount of invoice
+     * \return amount in euro
+     */
+    double get_amount() const
+    {
+        return amount_;
+    }
 
-	/**
- * \brief Implements the equality operator.
- */
-	bool operator ==(const invoice& e) const
-	{
-		return number_ == e.number_;
-	}
+    /**
+     * \brief Implements the equality operator.
+    */
+    bool operator ==(const invoice& e) const
+    {
+        return number_ == e.number_;
+    }
 
-	/**
-	 * \brief Implements the inequality operator.
-	 */
-	bool operator !=(const invoice& e) const { return !operator==(e); }
+    /**
+     * \brief Implements the inequality operator.
+     */
+    bool operator !=(const invoice& e) const { return !operator==(e); }
 };
 
 const char* invoice::categories[] = {
-	"Tanken",
-	"Nahrungsmittel",
-	"Reinigungsmittel",
-	"Urlaub",
-	"Haustiere",
-	"Bekleidung",
-	"Wohnen",
-	"Versicherung"
+    "Tanken",
+    "Nahrungsmittel",
+    "Reinigungsmittel",
+    "Urlaub",
+    "Haustiere",
+    "Bekleidung",
+    "Wohnen",
+    "Versicherung"
 };
 
 const char* invoice::months[] = {
-	"Januar",
-	"Februar",
-	"M\x84rz",
-	"April",
-	"Mai",
-	"Juni",
-	"Juli",
-	"August",
-	"September",
-	"Oktober",
-	"November",
-	"Dezember"
+    "Januar",
+    "Februar",
+    "M\x84rz",
+    "April",
+    "Mai",
+    "Juni",
+    "Juli",
+    "August",
+    "September",
+    "Oktober",
+    "November",
+    "Dezember"
 };
 
 /**
@@ -120,11 +120,11 @@ const char* invoice::months[] = {
 template <typename T>
 T ask_question(const string& question)
 {
-	cout << question << endl;
-	cout << "> ";
-	T value;
-	cin >> value;
-	return value;
+    cout << question << endl;
+    cout << "> ";
+    T value;
+    cin >> value;
+    return value;
 }
 
 void create_invoice();
@@ -142,7 +142,7 @@ void sum_invoices_per_category();
  */
 bool compare_month_ascending(const invoice& first, const invoice& second)
 {
-	return first.get_month() < second.get_month();
+    return first.get_month() < second.get_month();
 }
 
 /**
@@ -159,144 +159,159 @@ int invoice_serial_number;
  */
 int main()
 {
-	while (true)
-	{
-		system("cls");
-		cout << "Ausgabenverwaltung (" << invoices.size() << " Rechnungen)" << endl << endl;
-		cout << "Bitte w\x84hlen Sie eine Option:" << endl;
-		cout << "1: Erfassung einer Rechnung (inkl. Abfrage der Rechnungsdaten)" << endl;
-		cout << "2: Alle Ausgaben, sortiert nach Monat, ausgeben" << endl;
-		cout << "3: Summe der Ausgaben pro Kategorie ausgeben" << endl;
-		cout << "4: Rechnung l\x94schen" << endl;
-		cout << endl;
-		cout << "0: Programm beenden" << endl;
-		const auto input = ask_question<int>("Ihre Eingabe:");
+    while (true)
+    {
+        system("cls");
+        cout << "Ausgabenverwaltung (" << invoices.size() << " Rechnungen)" << endl << endl;
+        cout << "Bitte w\x84hlen Sie eine Option:" << endl;
+        cout << "1: Erfassung einer Rechnung (inkl. Abfrage der Rechnungsdaten)" << endl;
+        cout << "2: Alle Ausgaben, sortiert nach Monat, ausgeben" << endl;
+        cout << "3: Summe der Ausgaben pro Kategorie ausgeben" << endl;
+        cout << "4: Rechnung l\x94schen" << endl;
+        cout << endl;
+        cout << "0: Programm beenden" << endl;
+        const auto input = ask_question<int>("Ihre Eingabe:");
 
-		switch (input)
-		{
-		case 1:
-			create_invoice();
-			break;
-		case 2:
-			invoices_ordered_by_month();
-			break;
-		case 3:
-			sum_invoices_per_category();
-			break;
-		case 4:
-			delete_invoice();
-			break;
-		case 0:
-			return 0;
-		default:
-			cout << "Unerlaubte Eingabe" << endl;
-			system("pause");
-		}
-	}
+        switch (input)
+        {
+        case 1:
+            create_invoice();
+            break;
+        case 2:
+            invoices_ordered_by_month();
+            break;
+        case 3:
+            sum_invoices_per_category();
+            break;
+        case 4:
+            delete_invoice();
+            break;
+        case 0:
+            return 0;
+        default:
+            cout << "Unerlaubte Eingabe" << endl;
+            system("pause");
+        }
+    }
 }
 
 void create_invoice()
 {
-	system("cls");
-	cout << "Eine neue Rechnung erstellen" << endl;
-	cout << "------------------------------------" << endl;
-	const auto invoice_no = ++invoice_serial_number;
-	const auto amount = ask_question<double>("Bitte geben Sie den Betrag in Euro ein.");
-	const auto month = get_month();
-	const auto category = get_category();
-	const auto i = invoice(invoice_no, amount, month, category);
-	invoices.push_back(i);
+    system("cls");
+    cout << "Eine neue Rechnung erstellen" << endl;
+    cout << "------------------------------------" << endl;
+    const auto invoice_no = ++invoice_serial_number;
+    const auto amount = ask_question<double>("Bitte geben Sie den Betrag in Euro ein.");
+    const auto month = get_month();
+    const auto category = get_category();
+    const auto i = invoice(invoice_no, amount, month, category);
+    invoices.push_back(i);
 }
 
 void invoices_ordered_by_month()
 {
-	system("cls");
-	cout << "Alle Rechnungen nach Monat sortiert" << endl;
-	cout << "------------------------------------" << endl;
-	auto temp = list<invoice>(invoices);
-	temp.sort(compare_month_ascending);
-	for (auto invoice : temp)
-	{
-		cout << "  Rechnung: " << invoice.get_number() << endl;
-		cout << "  Betrag: " << invoice.get_amount() << " Euro" << endl;
-		cout << "  Monat: " << invoice::months[invoice.get_month()] << endl;
-		cout << "  Kategorie: " << invoice::categories[invoice.get_category()] << endl;
-		cout << "------------------------------------" << endl;
-	}
-	system("pause");
+    system("cls");
+    cout << "Alle Rechnungen nach Monat sortiert" << endl;
+    cout << "------------------------------------" << endl;
+    //<month, <category, amount>>
+    map<int, map<int, double>> month_category_amount;
+    for (auto invoice : invoices)
+    {
+        month_category_amount[invoice.get_month()][invoice.get_category()] += invoice.get_amount();
+    }
+
+    for (auto month_pair : month_category_amount)
+    {
+        auto sum = 0.0;
+        cout << invoice::months[month_pair.first] << endl;
+        cout << "------------------------------------" << endl;
+        for (const auto category_amount : month_pair.second)
+        {
+            cout << invoice::categories[category_amount.first] << ": " << category_amount.second << " Euro" << endl;
+            sum += category_amount.second;
+        }
+        cout << endl;
+        cout << "Gesamt: " << sum << " Euro";
+        if (sum > 500) cout << "  Mehr ausgegeben als geplant!!!";
+        cout << endl;
+        cout << "------------------------------------" << endl;
+    }
+    system("pause");
 }
 
 void delete_invoice()
 {
-	system("cls");
-	cout << "Rechnung l\x94schen" << endl;
-	cout << "------------------------------------" << endl;
-	const auto invoice_number = ask_question<int>("Bitte geben Sie eine Rechnungsnummer ein");
-	for (auto invoice : invoices)
-	{
-		if (invoice.get_number() == invoice_number)
-		{
-			invoices.remove(invoice);
-			return;
-		}
-	}
-	cerr << "Fehler: Rechnung nicht gefunden." << endl;
-	system("pause");
+    system("cls");
+    cout << "Rechnung l\x94schen" << endl;
+    cout << "------------------------------------" << endl;
+    const auto invoice_number = ask_question<int>("Bitte geben Sie eine Rechnungsnummer ein");
+    for (auto invoice : invoices)
+    {
+        if (invoice.get_number() == invoice_number)
+        {
+            invoices.remove(invoice);
+            return;
+        }
+    }
+    cerr << "Fehler: Rechnung nicht gefunden." << endl;
+    system("pause");
 }
 
 void sum_invoices_per_category()
 {
-	system("cls");
-	cout << "Summe der Ausgaben pro Kategorie ausgeben" << endl;
-	cout << "------------------------------------" << endl;
-	map<int, double> sums;
-	for (auto invoice : invoices)
-	{
-		sums[invoice.get_category()] = sums[invoice.get_category()] += invoice.get_amount();
-	}
-	for (const auto sum : sums)
-	{
-		cout << "  Kategorie: " << invoice::categories[sum.first] << endl;
-		cout << "  Summe: " << sum.second << " Euro" << endl;
-		cout << "------------------------------------" << endl;
-	}
-	system("pause");
+    system("cls");
+    cout << "Summe der Ausgaben pro Kategorie ausgeben" << endl;
+    cout << "------------------------------------" << endl;
+    map<int, double> sums;
+    for (auto invoice : invoices)
+    {
+        sums[invoice.get_category()] = sums[invoice.get_category()] += invoice.get_amount();
+    }
+    for (const auto sum : sums)
+    {
+        cout << "  Kategorie: " << invoice::categories[sum.first] << endl;
+        cout << "  Summe: " << sum.second << " Euro" << endl;
+        cout << "------------------------------------" << endl;
+    }
+    system("pause");
 }
 
 int get_month()
 {
-	while (true)
-	{
-		cout << "Bitte w\x84hlen sie einen Monat aus:" << endl;
-		auto index = 0;
-		for (auto month : invoice::months)
-		{
-			cout << ++index << ": " << month << endl;
-		}
-		const auto answer = ask_question<unsigned int>("");
-		if (answer > 0 && answer <= 12)
-		{
-			return answer - 1;
-		}
-		cout << "Ung\x81ltige Eingabe" << endl << endl;
-	}
+    while (true)
+    {
+        cout << "Bitte w\x84hlen sie einen Monat aus:" << endl;
+        auto index = 0;
+        for (auto month : invoice::months)
+        {
+            cout << ++index << ": " << month << endl;
+        }
+        const auto answer = ask_question<unsigned int>("");
+        const auto size = static_cast<int>(sizeof(invoice::months) / sizeof(*invoice::months));
+        if (answer > 0 && answer <= size)
+        {
+            return answer - 1;
+        }
+        cout << "Ung\x81ltige Eingabe" << endl << endl;
+    }
 }
 
 int get_category()
 {
-	while (true)
-	{
-		cout << "Bitte w\x84hlen sie eine Kategorie aus:" << endl;
-		auto index = 0;
-		for (auto category : invoice::categories)
-		{
-			cout << ++index << ": " << category << endl;
-		}
-		const auto answer = ask_question<int>("");
-		if (answer > 0 && answer <= 8)
-		{
-			return answer - 1;
-		}
-		cout << "Ung\x81ltige Eingabe" << endl << endl;
-	}
-}
+    while (true)
+    {
+        cout << "Bitte w\x84hlen sie eine Kategorie aus:" << endl;
+        auto index = 0;
+        for (auto category : invoice::categories)
+        {
+            cout << ++index << ": " << category << endl;
+        }
+        const auto answer = ask_question<int>("");
+        const auto size = static_cast<int>(sizeof(invoice::categories) / sizeof(*invoice::categories));
+        if (answer > 0 && answer <= size)
+        {
+            return answer - 1;
+        }
+        cout << "Ung\x81ltige Eingabe" << endl << endl;
+    }
+}
\ No newline at end of file