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 <stdlib.h>
#include <string.h>
int main(){
	char str[30];
	if(fgets(str, 30, stdin) == NULL){
		printf("error\n");
		exit(1);
	}

	int len = strlen(str);
	int count = 0;
	char* ans = "yes";
	for(int i=0;i<len;i++){
		for(int j=0;j<i;j++){
			if(str[i] == str[j]) ans = "no";
		}
	}

	printf("%s\n", ans);
	return 0;
}