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>
#include <algorithm>
using namespace std;

int main(){
  string s;
  cin >> s;
  vector<int> v(26);
  int flag = 1;

  for(int i = 0; i < s.length(); i++){
    v.at(s.at(i) - 'a')++;
    if(v.at(s.at(i) - 'a') >= 2){
      flag = 0;
      break;
    }
  }

  if(flag){
    cout << "yes" << endl;
  }
  else{
    cout << "no" << endl;
  }

  return 0;
}