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>

int main()
{
    int i,ch[27]={0},flag=0;
    char s[27];
    gets(s);
    for(i=0;i<strlen(s);i++)
    {
        if(ch[s[i]-'a']==0) ch[s[i]-'a']=1;
        else
        {
            flag=1;
            break;
        }
    }
    if(flag==1) printf("no");
    else printf("yes");
    return 0;
}