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 i,a[30];
	char s[30];
	scanf("%s",s);
	for(i=0;i<26;i++)
		a[i]=0;
	for(i=0;i<strlen(s);i++)
		a[s[i]-'a']++;
	for(i=0;i<26;i++){
		if(a[i]>1){
			printf("no\n");
			return 0;
		}
	}
	printf("yes\n");
	return 0;
}