#include <iostream>
using namespace std;

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