Envío 2023

Código

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

class Main{
	public static void main(String[] args) {
		Set<Character> set = new HashSet<Character>();
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.nextLine();
		boolean isRepeated = false;
		for (int i = 0; i < s.length(); i++) {
			if (!set.add(s.charAt(i))) {
				isRepeated = true;
			}
		}
		System.out.println(isRepeated ? "yes" : "no");

	}

}