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 n, m, i, j, t, k;
	char a[30];
	while(~scanf("%s", a)){
		char b[26];
		for(i = 0; i < 26; i++)  b[i] = 'a' + i;
		int c[26] = {0};
		int flag = 1;
		getchar();
		int str = strlen(a);
		for(i = 0; i < str; i++){
			for(j = 0; j < 26; j++)
				if(a[i] == b[j]) c[j]++;
		}
		for(i = 0; i < 26; i++)
			if(c[i] >= 2) flag = 0;
		if(flag) printf("yes\n");
		else printf("no\n");
	}
	return 0;
}