#include<fstream>
using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int fact(int x)
{
	if(x==0) return 1;
	  else return x*fact(x-1);
}
int main()
{
	int x;
	 cin>>x;
	cout<<fact(x);
 return 0;
}