#include <iostream>
#include <set>
#include <string>
using namespace std;
int main() {
	string s;
	set<char> c{};
	cin >> s;
	for (int i = 0; i < s.size(); i++) {
		c.insert(s[i]);
	}
	cout << (s.size() == c.size() ? "yes" : "no") << endl;
}
### Prompt

Construct a CPP code solution to the problem outlined:

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 <iostream>
#include <set>
#include <string>
using namespace std;
int main() {
	string s;
	set<char> c{};
	cin >> s;
	for (int i = 0; i < s.size(); i++) {
		c.insert(s[i]);
	}
	cout << (s.size() == c.size() ? "yes" : "no") << endl;
}
```