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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<iostream>
#include<string.h>
#include<ctype.h>
#include<string>
#include<math.h>
#define pi 3.141592653589
#include<iomanip>
using namespace std;
#include<algorithm>
#define rep(i,a,n) for(int i=a;i<n;i++)
#define INF 1e9
#define LINF 1e17
#define ll long long
#define MOD (int)(1e9+7)

int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};



int main(){
    
    int flag[1000]={};
    string s;
    
    cin>>s;
    rep(i,0,s.size()){
        if(flag[s[i]]){
            cout<<"no"<<endl;
            return 0;
        }
        else flag[s[i]]=1;
    }
    cout<<"yes"<<endl;
        
    return 0;
}