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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define REP(i, n) for(int i = 0; i < n; i++)
using namespace std;

int main() {
  string a; cin >> a;
  bool can = true;
  REP(i,a.size()){
    REP(j,a.size()){
      if(i == j) continue;
      if(a.at(i) == a.at(j))
      can = false;
    }
  }
if(can){
cout << "yes" << endl;
}
else cout << "no" << endl;

  return 0;
}