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;
using System.Linq;
using System.Collections.Generic;
public class Hello
{

    public static void Main()
    {
        string s = Console.ReadLine();
        string ans = "yes";
        for (int i = 0; i < s.Length; i++) {
            if (s.Count(c => c == s[i]) > 1) {
                ans = "no";
                break;
            }
        }
        Console.WriteLine(ans);
    }
}