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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict";
const Main = (input) => {
	let xs = input.trim().split('');
    let ans ='';
    for(let i =0; i <= xs.length; i++){
      if(xs[i]==xs[i+1]){
      ans="no";
      break;
      }else{
      ans="yes";  
      }
    }
     console.log(ans);
  }
Main(require('fs').readFileSync('/dev/stdin','utf8'));