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: Runtime Error)

#include <stdio.h>

int main()
{
	int a[27] = { 0 };
	int i, ans = 0;
	char s[27] = { 0 };

	scanf("%s", s);

	for (i = 0; s[i] != '\n'&& i < 27; i++){
		if (s[i] >= 'a' && s[i] <= 'z')
		++a[s[i] - 'a'];
	}
	for (i = 0; i < 27; i++){
		if (a[i] >= 2)
		{
			ans++;
		}
	}
	if (ans >= 1)
		printf("no\n");
	else
		printf("yes\n");

	return 0;
}