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)

// ABC 063 B Varied

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

bool is_not_duplicate(string str) {
  for (int i = 1; i < (int)str.size(); i++) {
    for (int j = 0; j < i; j++) {
      if (str[i] == str[j]) return false;
    }
  }
  return true;
}

string solve(string str) {
  return is_not_duplicate(str) ? "yes" : "no";
}

int main() {
  string str;
  cin >> str;
  cout << solve(str) << endl;
  return 0;
}