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: Wrong Answer)

#include<stdio.h>
int main(void){
	int i,j,k,null;
	int y=0;
	int n=0;
	char s[26];
	scanf("%s",s);
	
	for(k=0;k<26;k++){
		if(s[k]=='\0'){
			null=k;
			break;
		}
	}
	for(i=0;i<null-1;i++){
		for(j=i+1;j<null;j++){
			if(s[i]==s[j]){
				n=n+1;
			}else if(s[i]!=s[j]){
				y=y+1;
			}		
		}

	}
	
	if(y-n == y){
		printf("yes\n");
	}else if(y-n != y){
		printf("no\n",y);
	}
}