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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharp_TestCode
{
    class Program
    {
        static void Main(string[] args)
        {
            string S;
            S = Console.ReadLine();
            List<char> cList = new List<char>();

            foreach(char c in S)
            {
                cList.Add(c);
            }

            if (cList.Count != cList.Distinct().ToList().Count()) Console.WriteLine("no");
            else Console.WriteLine("yes");

        }

    }
}