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(void){
   char st[27],alp[26];
   int i,n;

   scanf("%s",st);
   n=strlen(st);

   for(i=0;i<26;i++)
      alp[i]=0;

   for(i=0;i<n;i++){
      alp[st[i]-'a']++;
      if(alp[st[i]-'a'] >= 2){printf("no\n");return 0;}
   }


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