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

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

  for(i = 1; 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");
  }

}