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: Accepted)

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>

using namespace std;

int main(void) {

	string s;
	int a[26] = { 0 }, co = 0;

	cin >> s;

	for (int i = 0; i < s.size(); i++) {
		if (a[(int)s[i] - 'a'] != 0) {
			co = 1;
			break;
		}
		a[(int)s[i] - 'a']++;
	}	

	if (co == 0) cout << "yes" << endl;
	else cout << "no" << endl;

	return 0;

}