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>
using namespace std;

int main()
{
    string S;
    cin >> S;

    vector<bool> occured(26);
    for (int i = 0; i < (int)S.size(); i++)
    {
        int c = S.at(i) - 'a';
        if (occured.at(c))
        {
            cout << "no" << endl;
            return 0;
        }
        occured.at(c) = true;
    }
    cout << "yes" << endl;
    return 0;
}