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>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>

int main(void){

    char S[27];

    scanf("%s", S);

    int c['z'-'a'+1];

    for(int i = 0; i <= 'z'-'a'; i++){
        c[i] = 0;
    }

    for(int i = 0; i < strlen(S); i++){
        c[S[i]-'a']++;
    }

    int t = 1;

    for(int i = 0; i < strlen(S); i++){
        if(c[i] >= 2){
            t = 0;
            break;
        }
    }

    if(t == 1){
        printf("yes\n");
    }else{
        printf("no\n");
    }

    return 0;
}