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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.TreeSet;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		TreeSet<Character> ts = new TreeSet<>();
		String s = scan.next();
		for (int i = 0; i < s.length(); i++) {
			ts.add(s.charAt(i));
		}
		if (ts.size() == s.length()) {
			System.out.println("yes");
		} else {
			System.out.println("no");
		}
	}

}