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: Time Limit Exceeded)

#include<stdio.h>
int main(){
char s[26];
int i,j,k;
k=0;
scanf("%s",&s[26]);
for(i=0;i<26;i++){
for(j=1;j<26;j=i+1){
if('s[i]'=='s[j]'){
printf("no\n");
k++;
break;
}
}
}
if(k==0){
printf("yes\n");
}
return 0;
}