username

import java.util.Scanner;

public class userName {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String username = scanner.nextLine();
        String[] input = scanner.nextLine().split(" ");
        while (!input[0].equals("Sign up")) {
            String command = input[0];
            switch (command) {
                case "Case":
                    if (input[1].equals("Upper")) {
                        username = username.toUpperCase();
                    } else {
                        username = username.toLowerCase();
                    }
                    System.out.println(username);
                    break;
                case "Reverse":
                    int firstIndex = Integer.parseInt(input[1]);
                    int secondIndex = Integer.parseInt(input[2]);
                    if (firstIndex >= 0 && secondIndex < username.length()) {
                        String reversed = username.substring(firstIndex, secondIndex + 1);
                        StringBuilder rev = new StringBuilder();
                        rev.append(reversed);
                        rev.reverse();
                        System.out.println(rev);
                    }
                    break;
                case "Cut":
                    String substring = input[1];
                    if (username.contains(substring)){
                        username = username.replace(substring,"");
//                    int firstIndex = username.indexOf(substring);
//                    int secondIndex = firstIndex+substring.length();
//                        username = username.substring(0,firstIndex).concat(username.substring(secondIndex));
                        System.out.println(username);

                    } else System.out.printf("The word %s doesn't contain %s.%n",username, substring);
                    break;
                case "Replace":
                    String Char = input[1];
                    username = username.replace(Char, "*");
                    System.out.println(username);
                    break;

                case "Check":
                    String check = input[1];
                    if (username.contains(check)) {
                        System.out.printf("Valid");
                    } else
                        System.out.printf("Your username must contain %s.%n", check);
                    break;

            }
            input = scanner.nextLine().split(" ");
        }
    }
}