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>
#include <string.h>

int main(){

  char memo[27];
  char S[27];
  scanf("%s", S);
  strcpy(memo, S);


  for(int i=0;i<strlen(S);i++){
    for(int j=i+1;j<strlen(memo);j++){
//      printf("%d-%d\n", i, j);
      if(S[i] == memo[j] && i!=j ){
        printf("no\n");
        return 0;
      }
    }
  }

  printf("yes\n");
  return 0;

}