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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;

int main() {
  string s;
  std::cin >> s;

  sort(s.begin(), s.end());
  bool ok = true;
  rep(i, s.size() - 1) {
    if (s[i] == s[i + 1]) {
      ok = false;
    }
  }

  std::cout << (ok ? "yes" : "no") << std::endl;
  return 0;
}