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 <iostream>
#include <algorithm>
#include <cmath>
#include <limits>
using namespace std;

int main (void) {
  string s;
  cin >> s;
  bool flag= true;
  int N=s.length();
  sort(s.begin(), s.end());
  for (int i=0; i<=N-2; i++) {
    if (s[i] == s[i+1]){
      cout << "no";
      flag =false;
      break;
    }
  }
  if (flag =true) {
  cout << "yes";
  }
}