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)

function main (input) {
    const S = input.split('');
    var ans = 'yes';

    for (var i = 0; i < S.length; i++){
        for (var j = i+1; j < S.length -j; j++) {
            if (S[i] === S[j]) {
            ans = 'no';
            }
        }
    }
    console.log(ans);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));