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 <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#define MOD 1000000007
#define ll long long

int cmpfunc(const void *a, const void *b){
    return (*(int*)a - *(int*)b);
}

int max(int a,int b){
    return (a>b)?a:b;
}

int main(void){
    char s[100];
    scanf("%s",s);
    int len=strlen(s);
    int a[26];
    int i;
    for(i=0;i<26;i++) a[i]=0;
    for(i=0;i<len;i++) a[s[i]-'a']++;
    for(i=0;i<26;i++){
        if(a[i]>1) break;
    }
    if(i>=26) printf("yes\n");
    else printf("no\n");


    return 0;
}