#include <iostream>
 
constexpr int factorial(int n) // Everything here is known at compile time
{
    return n <= 1 ? 1 : (n * factorial(n - 1));
}
 
int main(void)
{
    int i;
    std::cin >> i;
	const int f = factorial(i); // I really can't guess this at compile time..
	std::cout << f << std::endl;
	return 0;
}
				I2luY2x1ZGUgPGlvc3RyZWFtPgoKY29uc3RleHByIGludCBmYWN0b3JpYWwoaW50IG4pIC8vIEV2ZXJ5dGhpbmcgaGVyZSBpcyBrbm93biBhdCBjb21waWxlIHRpbWUKewogICAgcmV0dXJuIG4gPD0gMSA/IDEgOiAobiAqIGZhY3RvcmlhbChuIC0gMSkpOwp9CgppbnQgbWFpbih2b2lkKQp7CiAgICBpbnQgaTsKICAgIHN0ZDo6Y2luID4+IGk7Cgljb25zdCBpbnQgZiA9IGZhY3RvcmlhbChpKTsgLy8gSSByZWFsbHkgY2FuJ3QgZ3Vlc3MgdGhpcyBhdCBjb21waWxlIHRpbWUuLgoJc3RkOjpjb3V0IDw8IGYgPDwgc3RkOjplbmRsOwoJcmV0dXJuIDA7Cn0=