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;
class MyMain
{
    static void Main()
    {
        string s = System.Console.ReadLine().Trim();
        int flag=0;
        for(int i=0;i < s.Length;i++)
        {
            if (s.Length - s.Replace(s[i].ToString(), "").Length > 1) { flag = 1; break; }
        }
        System.Console.WriteLine(flag == 0 ? "yes" : "no");
        System.Console.ReadLine();
    }
}