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(int argc, char *argv[])
{
	int i, j, len;
	int flag = 0;
	char input[30];

	scanf("%s", input);
	len = strlen(input);


	for (i = 0; i < len - 1; i++) {
		for (j = i + 1; j < len; j++) {
			if (input[i] == input[j]) {
				printf("no");
				exit(0);
			}
		}
	}
	printf("yes");

	return(0);
}