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(){
    int c[26] = {0};
    char s[30];
    scanf("%s",s);
    int len,flag;
    flag = 0;
    len = strlen(s);
    for(int i = 0;i < len;i++)
        c[s[i]-'a']++;
    for(int i = 0;i < 26;i++){
        if(c[i]>1){
            printf("no\n");
            flag = 1;
            break;
        }
    }
    if(flag==0) printf("yes\n");
    return 0;
}