Merkkijono

import java.util.Objects;
import java.util.Scanner;
 
public class Merkkijono {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String string = input.nextLine();
        while (true) {
            int length = string.length();
            for (int i = 0; i + 1 < length; i++) {
                int endIndex = 0;
                for (int i2 = i + 1; i2 < length; i2++) {
                    if (Objects.equals(string.charAt(i), string.charAt((i2)))) {
                        endIndex = i2;
                    }
                    else {
                        break;
                    }
                }
                if (endIndex != 0) {
                    if (i != 0) {
                        string = string.substring(0, i) + string.substring(endIndex + 1, length);
                    }
                    else {
                        string = string.substring(endIndex + 1, length);
                    }
                    break;
                }
            }
            if (string.length() == length) {
                break;
            }
        }
        System.out.println(string);
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED