#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

const int NUMBER {15};
int main() {
    double part1 {pow(M_E, -NUMBER)}, 
           part2, 
           part3;
    double approximation;
    long actualValue;
    float silly {1};

    cout << "Just a demo of showpoint " << endl;
    cout << " Without " << silly << endl;
    cout << showpoint;
    cout << "With     " << silly << endl;

    //actualValue = static_cast<long>(15)*14*13*12*11*10*9*8*7*6*5*4*3*2;
    actualValue = 15L*14*13*12*11*10*9*8*7*6*5*4*3*2;

    part2 = pow(NUMBER, NUMBER);
    part3 = sqrt(2 * M_PI * NUMBER) ;

    approximation = part1 * part2 * part3;

    //cout << fixed;
    //cout << setprecision(0);

    cout << NUMBER << "! is about " << approximation << endl;
    cout << NUMBER << "! is       " << actualValue << endl;

    
    return 0;
}