#include<iostream>
using namespace std;
int main(){
  int n;
  long a=1;
  cin>>n;
  for(;n!=0;n--){
    a*=n;
  }
  cout<<a<<endl;
}
### Prompt

Create a solution in CPP for 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;
  long a=1;
  cin>>n;
  for(;n!=0;n--){
    a*=n;
  }
  cout<<a<<endl;
}
```