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>
int main(void) {
	char s[30];
	scanf("%s", s);
	for (int i = 0; s[i] != 0; i++)
	{
		for (int j = i - 1; j >= 0; j--)
		{
			if (s[j] == s[i])
			{
				printf("no");
				goto end;
			}
		}
	}
	printf("yes");
end:
	return 0;
}