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 B {
	class Program {
		static bool[] haved = new bool[26];
		static void Main(string[] args) {
			string uinps = Console.ReadLine();
			foreach (var item in uinps) {
				if (haved[item - 'a']) {
					Console.WriteLine("no");
					return;
				}
				haved[item - 'a'] = true;
			}
			Console.WriteLine("yes");
			return;
		}
	}
}