#include <iostream>
#include <vector>
#include <algorithm>

unsigned int factorial(unsigned int n){
	if(n==0){
		return 1;
	}	else{
		return factorial(n-1)*n;
	}
}

int main(){
	unsigned int n;
	std::cin >> n;
	std::cout << factorial(n) << std::endl;
	return 0;
}