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: Accepted)

function Main(input) {
	input = input.trim();
  var list = "abcdefghijklmnopqrstuvwxyz".split("");
  for(var i = 0; i < input.length; i++){
    var tmp = input.slice(i , i + 1);
    if(list.indexOf(tmp) != -1){
       list.splice(list.indexOf(tmp), 1);
       }else{
         console.log("no");
         return;
       }
  }
  console.log("yes");
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));