Envío 2455

Código

import java.util.Scanner;

/**
 *
 * @author usuario
 */
public class Main {

    public static void main(String[] args) throws java.lang.Exception {
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        boolean[] letters = new boolean[128];
        String result = "yes";
        for(int i=0; i<word.length();i++){
            int item = word.charAt(i);
            if(letters[item]){
                result = "no";
                break;
            }else{
                letters[item] = true;
            }
        }
        System.out.println(result);
    }
}