#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
 #include<functional>

#define INPUT_FROM_FILE (0) 
#if INPUT_FROM_FILE
#include <fstream>
#endif

int main(int argc, char **argv){
	int n = 0;
	long long ans = 1;

#if INPUT_FROM_FILE
	std::ifstream ifs("test.txt");
#endif

#if INPUT_FROM_FILE
	ifs >> n;
#else
	std::cin >> n;
#endif

	for(int i = 1; i <= n; i++){
		ans *= i;
	}

	std::cout << ans << std::endl;
	return 0;
}
