#include<iostream>
using namespace std;
int main(){
	int n;
	long long ans;
	cin >> n;
	ans = 1;
	for(int i = 1; i <= n; i++){
		ans *= i;
	}
	cout << ans << endl;
}
### Prompt

Develop a solution in Cpp to the problem described below:

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<iostream>
using namespace std;
int main(){
	int n;
	long long ans;
	cin >> n;
	ans = 1;
	for(int i = 1; i <= n; i++){
		ans *= i;
	}
	cout << ans << endl;
}
```