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)

#define _CRT_SECURE_NO_WARNINGS
//#define DEBUG
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>

int printkigou(int, char);

int main(void) {
#ifdef DEBUG
	printf("");
#endif

	char S[26] = { '\0' };
	int i,j;
	int flag = 0;

	scanf("%s", S);

	for (i = 0; i < 26; i++) {
		if (S[i] == '\0') {
			break;
		}

		for (j = i+1; j <26; j++) {
			if (S[j] == '\0') {
				break;
			}
			if (S[i] == S[j]) {
				flag = 1;
				break;
			}
		}
		if (flag == 1) {
			break;
		}

	}
	if (flag == 0) {
		printf("yes\n");
	}
	else {
		printf("no\n");
	}

	return 0;
}