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

### Prompt

In CPP, your task is to solve 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 <iostream>
using namespace std;
int main(){
    int n;
    cin>>n;
    long s=1;
    for(int i=1; i<=n; i++)
        s*=i;
    cout<<s<<endl;
}

```