#include <bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin >> n;
	long long sum = 1;
	for (int i = 1; i <= n; ++i) {
		sum *= i;
	}
	cout << sum << endl;
}
### Prompt

Please formulate a cpp solution to the following problem:

Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.



Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Example

Input

5


Output

120

### Response

```cpp
#include <bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin >> n;
	long long sum = 1;
	for (int i = 1; i <= n; ++i) {
		sum *= i;
	}
	cout << sum << endl;
}
```