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;

namespace AtCoder
{
	class Program
	{
		static void Main(string[] args)
		{
			Question.Exec();
		}
	}

	public static class Question
	{
		public static void Exec()
		{
			string s = Console.ReadLine();
			char[] chars = s.ToArray();
			var chars2 = chars.Distinct().ToArray();
			if (chars.Length == chars2.Length)
			{
				Console.WriteLine($"yes");
			} else
			{
				Console.WriteLine($"no");
			}

			Console.ReadKey();
		}
	}
}