#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  cin>>s;
  int sz=s.size();
  for(int i=0;i<sz;i++){
    for(int j=i+1;j<sz;j++){
      if(s[i]==s[j]){ cout<<"no"; return 0; }
      else continue;
    }
  }
  cout<<"yes";

}

### Prompt

Please create a solution in Cpp to the following problem:

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`.

Examples

Input

uncopyrightable


Output

yes


Input

different


Output

no


Input

no


Output

yes

### Response

```cpp
#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  cin>>s;
  int sz=s.size();
  for(int i=0;i<sz;i++){
    for(int j=i+1;j<sz;j++){
      if(s[i]==s[j]){ cout<<"no"; return 0; }
      else continue;
    }
  }
  cout<<"yes";

}

```