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;
 
namespace ConsoleApplication32
{
    class Program
    {
        static void Main(string[] args)
        {
			string str = Console.ReadLine();
			string r = "";
			foreach(char mizutani in str)
			{
				foreach(char yagi in r)
				{
					if(yagi == mizutani)
					{
						Console.WriteLine("no");
						return;
					}
				}
				r += mizutani;
			}
			Console.WriteLine("yes");
        }
    }
}