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 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <string.h>

#define N 26

int main() {
	static char s[N + 1];
	static int kk[N];
	int n, i;

	scanf("%s", s);
	n = strlen(s);
	for (i = 0; i < n; i++)
		kk[s[i] - 'a']++;
	for (i = 0; i < n; i++)
		if (kk[s[i] - 'a'] != 1) {
			printf("no\n");
			return 0;
		}
	printf("yes\n");
	return 0;
}