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[27];
  scanf("%s", s);
  int check[26];
  for (int i = 0; i < 26; i++) {
    check[i] = 0;
  }
  int flag = 1;
  for (int i = 0; i < 27; i++) {
    if (s[i] < 'a' || s[i] > 'z') {
      break;
    }
    check[s[i]-'a']++;
    if (check[s[i]-'a'] > 1) {
      flag = 0;
      break;
    }
  }
  if (flag == 1) {
    printf("yes\n");
  } else {
    printf("no\n");
  }

  return 0;
}