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 9.2.1) (judge verdict: Accepted)

#include<stdio.h>
#include<string.h>

int main(void)
{
   int i, f;
   char s[27];

   scanf("%s",s);

   for(i=0;i<strlen(s)-1;i++)
      for(f=i+1;f<strlen(s);f++)
         if(s[i]==s[f]){
            printf("no\n");
            return 0;
         }

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