#include <iostream>
#include <string>

using namespace std;


int main(void){
	unsigned long long n;
	cin >> n;
	unsigned long long kakunou = n;
	unsigned long long loop = n + 1;
	for (unsigned long long i = 0; i < loop; ++i){
		
		if (n == 1){
		
			break;
		}

		kakunou = kakunou * (n - 1);
		n -= 1;
		
	}
	cout  << kakunou << endl;
	return 0;

}