Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.

Constraints

2 ≤ |S| ≤ 26, where |S| denotes the length of S.

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If all the characters in S are different, print yes (case-sensitive); otherwise, print no.

Sample Input 1

uncopyrightable

Sample Output 1

yes

Sample Input 2

different

Sample Output 2

no

Sample Input 3

no

Sample Output 3

yes

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

public class Hello{
  public static void Main(){
    string s = Console.ReadLine();
    
    string cnt = "yes";
    
    int i, j;
    
    for( i = 0 ; i < s.Length ; i++){
      
      for(j = i+1 ; j < s.Length ; j++){
        if( s[i] == s[j] ){
          cnt = "no";
        }
        
      }
      
    }
    
    Console.WriteLine(cnt);
  }
}