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()
{
  char s[27];
  scanf("%s",&s);
  int i;
  i = 0;
  int j;
  while (s[i])
  {
    j = i + 1;
    while (s[j])
    {
      if (s[i] == s[j])
      {
        printf("no");
        return (0);
      }
      j++;
    }
    i++;
  }
  printf("yes");
}