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 c[25];
  int f=0,len,i,j;
  scanf("%s", c);
  len = strlen(c);
  
  for(i=0;i<len;i++){
    for(j=i+1;j<len;j++){
      if(c[i] == c[j]){
	f = 1;
      }
    }
  }
  if(f == 0){
    printf("yes\n");
  }else{
    printf("no\n");
  }
  return 0;
}