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>

int main()
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);

  std::string S;
  std::cin >> S;
  int n = S.size();
  std::string ans = "yes";
  for(int i=0; i<n; i++)
    for(int j=0; i<n; j++)
      if(S[i] == S[j])
      {
        ans = "no";
        break;
      }
  std::cout << ans <<'\n';
}