#include <iostream>
#include <cstdlib>
#include <ctime>

#define DIV (rand() - 1) / 32766.0      // defining a macro - everytime when we put DIV, it's replaced by this formula (rand() - 1) / 32766.0

using namespace std;

double PI_number(unsigned long long N)
{
    double x, y;
    unsigned long long n = 0;       // counts the number of the points included of the circle
    srand(time(nullptr));
    for(unsigned i = 0; i < N; ++i)
    {
        x = DIV;
        y = DIV;
        if(x * x + y * y <= 1)
            ++n;
    }
    return 4.0 * n / N;
}

int main()
{
    cout << "PI has been estimated at " << PI_number(10000000000) << endl;
    return 0;
}