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>

int main(void) {
	char s[27];
	char check[26] = { 0 };
	scanf("%s", s);
	int len = strlen(s);
	for (int i = 0; i < len; ++i) {
		if (check[s[i] - 97]) {
			printf("no");
			return 0;
		}
		check[s[i] - 97] = 1;
	}
	printf("yes");

	return 0;
}