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: Time Limit Exceeded)

#include <stdio.h>
 
int main(void) {

char S[26];
scanf("%s", S);
int n = sizeof(S);
int i, j;
int a = 0;

for(i = 0; i <= n; ++i){
  for(j = i + 1; j <= n; ++j){
     if(S[i]==S[j]){
        a = a + 1;
     }
  }
}
  
if(a > 0){
 printf("no\n");
 } else {
   printf("yes\n");
 }

}