#include <bits/stdc++.h>
using namespace std;
 
int main() {
	long long int n, sum=1;
	cin>>n;
	for(int i=0;i<n;i++){
		sum=sum*(n-i);
	}
	cout<<sum<<endl;
}

### Prompt

Your challenge is to write 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() {
	long long int n, sum=1;
	cin>>n;
	for(int i=0;i<n;i++){
		sum=sum*(n-i);
	}
	cout<<sum<<endl;
}

```