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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

int main() {
  int n,x;
  string s;
  cin >> s;
  n = s.size();
  x = 0;
  for(int i=0;i<n-1;i++){
    for(int j=i;j<n;j++){
      if(s.at(i) = s.at(j)){
        x++;
        break;
      }
    }
    if(x>0){
      break;
    }
  }
  
  if(x==0){
    cout << "yes" << endl;
  }
  else {
    cout << "no" << endl;
  }
}