#include<bits/stdc++.h>
using namespace std;
int main()
{

string s;
int a,b,i,j,l;
set<char>q;
cin>>s;
for(i=0;i<s.size();i++)
{
  q.insert(s[i]);
}
if(s.size()==q.size())
cout<<"yes\n";
else cout<<"no\n";
}
### Prompt

Create a solution in Cpp for 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;
int a,b,i,j,l;
set<char>q;
cin>>s;
for(i=0;i<s.size();i++)
{
  q.insert(s[i]);
}
if(s.size()==q.size())
cout<<"yes\n";
else cout<<"no\n";
}
```