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(){
    int book[30] = {0};
    char ch;
    while((ch = getchar()) != '\n'){
        book[ch - 'a']++;
    }
    int flag = 1;
    for(int i=0; i<26; i++){
        if(book[i] >= 2){
            printf("no");
            flag = 0;
            break;
        }
    }
    if(flag) printf("yes");
    return 0;
}