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(int argc, char *argv[]) {
    char s[26];

    scanf("%s", s);

    for (int j = 0; j < strlen(s); j++) {
        for (int i = 0; i < strlen(s); i++) {
            if ((i != j) && (s[i] == s[j])) {
                puts("no");
                return 0;
            }
        }
    }

    puts("yes");

    return 0;
}