diff --git a/Vorbereitungen/Konto.java b/Vorbereitungen/Konto.java
new file mode 100644
index 0000000..978ad4c
--- /dev/null
+++ b/Vorbereitungen/Konto.java
@@ -0,0 +1,97 @@
+import java.util.Scanner;
+
+public class Konto {
+    static double kontostand;
+    static Scanner scanner;
+
+    private static boolean isInt(String input) {
+        try {
+            Integer.parseInt(input);
+        } catch (NumberFormatException nfe) {
+            return false;
+        }
+        return true;
+    }
+
+    private static void showBalance() {
+        System.out.printf("Kontostand: %f", kontostand);
+    }
+
+    private static void deposit() {
+        System.out.printf("Bitte geben Sie an, wie viel Geld sie einzahlen möchten: ");
+        String userInput;
+        while (true) {
+            userInput = scanner.nextLine();
+            if (isInt(userInput)) {
+                Double.parseDouble(userInput);
+                break;
+            } else {
+                System.out.println("Bitte geben Sie eine ganze Zahl ein.");
+            }
+        }
+        double cleanUserInput = Double.parseDouble(userInput);
+        kontostand += cleanUserInput;
+    }
+
+    private static void withdraw() {
+        System.out.printf("Bitte geben Sie ein, wie viel Sie abheben möchten: ");
+        String userInput;
+        while (true) {
+            userInput = scanner.nextLine();
+            if (isInt(userInput)) {
+                Double.parseDouble(userInput);
+                break;
+            } else {
+                System.out.println("Bitte geben Sie eine ganze Zahl ein.");
+            }
+            double cleanUserInput = Double.parseDouble(userInput);
+            if (cleanUserInput > kontostand) {
+                System.out.println("Der eingegebene Betrag ist größer als der Kontostand.");
+                return;
+            }
+            kontostand -= cleanUserInput;
+        }
+
+    }
+
+    private static void menu() {
+        System.out.println("1. Kontostandanzeige");
+        System.out.println("2. Einzahlung");
+        System.out.println("3. Auszahlung");
+        System.out.println("4. Verlassen");
+        System.out.printf("Eingabe: ");
+        String userInput;
+        while (true) {
+            userInput = scanner.nextLine();
+            if (isInt(userInput)) {
+                Integer.parseInt(userInput);
+                break;
+            } else {
+                System.out.println("Bitte geben Sie eine ganze Zahl ein.");
+            }
+        }
+        int cleanUserInput = Integer.parseInt(userInput);
+        while (true) {
+            switch (cleanUserInput) {
+                case 1:
+                    showBalance();
+                    break;
+                case 2:
+                    deposit();
+                    break;
+                case 3:
+                    withdraw();
+                    break;
+                case 4:
+                    System.out.println("Verlassen...");
+                    System.exit(0);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        kontostand = 0;
+        scanner = new Scanner(System.in);
+        menu();
+    }
+}
diff --git a/Vorbereitungen/MonteCarlo/manifest.txt b/Vorbereitungen/MonteCarlo/manifest.txt
new file mode 100644
index 0000000..733d413
--- /dev/null
+++ b/Vorbereitungen/MonteCarlo/manifest.txt
@@ -0,0 +1,2 @@
+Main-Class: vorbereitungen.MonteCarlo.MonteCarlo
+
diff --git a/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/MonteCarlo.java b/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/MonteCarlo.java
new file mode 100644
index 0000000..2a362f4
--- /dev/null
+++ b/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/MonteCarlo.java
@@ -0,0 +1,52 @@
+package vorbereitungen.MonteCarlo;
+
+import java.util.Scanner;
+
+public class MonteCarlo {
+    public static void main(String args[]) {
+        Scanner scanner = new Scanner(System.in);
+        System.out.println("Enter how many attempts you want to run:");
+        String attempts = scanner.nextLine();
+
+        try {
+            int num_attempts = Integer.parseInt(attempts);
+        } catch(NumberFormatException nfe) {
+            System.out.println("Invalid input.");
+            scanner.close();
+            System.exit(1);
+            return;
+        }
+        int num_attempts = Integer.parseInt(attempts);
+
+        System.out.println("Enter how large the initial bankroll should be:");
+        String bankroll = scanner.nextLine();
+
+        try {
+            int num_bankroll = Integer.parseInt(bankroll);
+        } catch(NumberFormatException nfe) {
+            System.out.println("Invalid input.");
+            scanner.close();
+            System.exit(1);
+            return;
+        }
+        int num_bankroll = Integer.parseInt(bankroll);
+
+        System.out.println("Enter the Betsize you want to use for this simulation:");
+        String betsize = scanner.nextLine();
+
+        try {
+            int num_betsize = Integer.parseInt(betsize);
+        } catch(NumberFormatException nfe) {
+            System.out.println("Invalid input.");
+            scanner.close();
+            System.exit(1);
+            return;
+        }
+        int num_betsize = Integer.parseInt(betsize);
+
+        scanner.close();
+
+        Simulation simulation = new Simulation(num_attempts, num_bankroll, num_betsize);
+        simulation.run();
+    }
+}
diff --git a/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/Simulation.java b/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/Simulation.java
new file mode 100644
index 0000000..b1aeb2d
--- /dev/null
+++ b/Vorbereitungen/MonteCarlo/src/vorbereitungen/MonteCarlo/Simulation.java
@@ -0,0 +1,67 @@
+package vorbereitungen.MonteCarlo;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class Simulation{
+    int max_attempts;
+    int current_attempts;
+    double starting_bankroll;
+    double current_bankroll;
+    double simulated_betsize;
+
+    public Simulation(int max_atts, int bankroll, double betsize) {
+         this.max_attempts = max_atts;
+         this.current_attempts = 1;
+         this.starting_bankroll = bankroll;
+         this.current_bankroll = bankroll;
+         this.simulated_betsize = betsize;
+    }
+
+    public static int roll() {
+        return ThreadLocalRandom.current().nextInt(1, 8);
+    }
+
+    public static double calculate(int player_roll, int dealer_roll) {
+        int diff = dealer_roll - player_roll;
+        if (diff >= 1) {return 0;}
+        else if (diff == 0) {return 1;}
+        else if (diff == -6) {return 2;}
+        else {return 1.5;}
+    }
+
+    public void handle() {
+        if (this.simulated_betsize > this.current_bankroll) {
+            System.out.println("|===Out of money===|");
+            System.out.printf("|Attempts: %d      |\n", this.current_attempts);
+            System.out.println("===================|");
+            System.exit(2137);
+        }
+        this.current_bankroll -= this.simulated_betsize;
+        int player_roll = roll();
+        int house_roll = roll();
+        double mult = calculate(player_roll, house_roll);
+        this.current_bankroll += this.simulated_betsize*mult;
+        this.current_attempts++;
+    }
+
+    public void print_progress() {
+        double bankroll_percentage = (this.current_bankroll/this.starting_bankroll)*100;
+        double attempt_percentage = (this.current_attempts/this.max_attempts)*100;
+        System.out.printf("\033[2J"); // Clear screen
+        System.out.println("|===========|");
+        System.out.printf("|Current Attempt: %d/%d|\n", this.current_attempts, this.max_attempts);
+        System.out.printf("|Current Bankroll: %f|\n", this.current_bankroll);
+        System.out.printf("|%f%% left of starting bankroll\n|", bankroll_percentage);
+        System.out.printf("|%f%% done|", attempt_percentage);
+        System.out.println("|===========|");
+    }
+
+    public void run(){
+        for (int i = 0; i < max_attempts; i++) {
+            handle();
+            if (this.current_attempts % 7500 == 0 || this.current_attempts == 1) {
+                print_progress();
+            }
+        }
+    }
+}
diff --git a/Vorbereitungen/SieveOfErathostenes.java b/Vorbereitungen/SieveOfErathostenes.java
new file mode 100644
index 0000000..ceb98a3
--- /dev/null
+++ b/Vorbereitungen/SieveOfErathostenes.java
@@ -0,0 +1,58 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class SieveOfErathostenes {
+    private static void isValid(String input) {
+        if (input == null) {System.exit(-1);}
+        try {
+            Integer.parseInt(input);
+        } catch (NumberFormatException nfe) {
+            System.out.println("Die eingegebene Zahl ist keine ganze Zahl");
+            System.exit(-1);
+        }
+        int cleanInput = Integer.parseInt(input);
+        if (cleanInput < 2 || cleanInput > 1000) {
+            System.out.println("Die eingegebene Zahl muss mindestens 2 sein und höchstens 1000 sein.");
+            System.exit(-1);
+        }
+    }
+
+    private static void printArray(boolean[] arr) {
+        for (int i = 0; i < arr.length; i++) {
+            if (arr[i]) {
+                System.out.printf("%d ", i + 2);
+            }
+        }
+        System.out.printf("%n");
+    }
+
+
+    public static void main(String[] args) {
+        //System.out.println("Sanity Check");
+        Scanner input_scanner = new Scanner(System.in);
+        System.out.println("Bitte gib eine Zahl ein. ");
+        String user_input = input_scanner.nextLine();
+        input_scanner.close();
+        isValid(user_input);
+        int clean_input = Integer.parseInt(user_input);
+
+        boolean[] primes = new boolean[clean_input];
+        Arrays.fill(primes, true);
+
+        for (int i = 1; i < clean_input; i++) {
+            if (i == 1) {continue;}
+            if (primes[i]) {
+                for (int j = 2; j < clean_input; j++) {
+                    int tmp = j*i;
+                    if (tmp > clean_input) {
+                        break;
+                    }
+                    primes[tmp - 2] = false;
+                }
+            }
+        }
+
+        primes[clean_input - 1] = false;
+        printArray(primes);
+    }
+}