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 <cmath>


using namespace std;
int main()
{
	string s;
	cin >> s;

	bool exist_different = false;

	for (int i = 0; i < s.size() - 1; i++) {
		for (int j = i + 1; j < s.size(); j++) {
			if (s[i] == s[j]) exist_different = true;
		}
	}

	if (exist_different) cout << "no" << endl;
	else cout << "yes" << endl;

	return 0;
}