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 ABC0603
{
	class Program
	{
		static void Main(string[] args)
		{
			var param = Console.ReadLine();

			var param2 = param.Distinct();
			var param3 = param.ToList();

			if(param2.Count() == param3.Count())
			{
				Console.WriteLine("yes");
			}
			else
			{
				Console.WriteLine("no");
			}
		}
	}
}