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( str ){
      var result = "yes";
      for( var i=0; i<str.length; i++ ){
        var cnt = 0;
        for( var k=0; k<str.length; k++ ){
          if( str[i] == str[k] ) cnt++;
        }
        if( cnt > 1 ) result = "no";
      }
      console.log( result );
    }
     
    main(require("fs").readFileSync("/dev/stdin", "utf8"));