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)
{
	int i,t,lon,count=0;
	char s[27];
	scanf("%s",s);
	
	lon=strlen(s);
	
	for(i=0;i<lon;i++){
		for(t=i+1;t<lon;t++){
			if(s[i]==s[t]){
				count++;
			}
		}
	}
	
	if(count!=0){
		printf("no\n");
	} else{
		printf("yes\n");
	}
	return 0;
}