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

using namespace std;

const int NUMBER {15};

int main() {

    double part1{pow(M_E,-NUMBER)},
           part2,
           part3,
           approximation;

    long actualValue;

    float x = 1;

    cout << "X without showpoint " << x << endl;
    cout << showpoint;
    cout << "X with showpoint    " << x << 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 << scientific;
    //cout << setprecision(0);
/*
    cout << "       123456789012345" << endl;
    cout << "pi = " << M_PI << endl;
    cout << "e  = " << M_E << endl;
*/


    cout << NUMBER << "! is about " << approximation << endl;
    cout << NUMBER << "! is       " << actualValue << endl;
    return 0;
}