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

using namespace std;

double pi = 3.14159265358;

double Paul(double x, double eps)
{
    double y = 1, summa = 0, last = 1;;
    for (; fabs(last) > eps;)
    {
        last = pow(-1, y) * pow(x, 2 * y - 1) / (2 * y - 1);
        summa += last;
        y+=1;
    }
    return pi/2 + summa;
}

double Harry(double x, double eps)
{
    double summ = pi/2 - x, x2n_1 = -x;
    x *= x;

    for(int k = 3; fabs(x2n_1/k) > eps; k += 2)
    {
        x2n_1 *= -x;
        summ += x2n_1/k;
    }
    return summ;
}

int main()
{
    for(double x = 0; x <= 0.9; x += 0.1)
    {
        cout << setw(4) << x
            << setw(12) << pi/2-atan(x)
            << setw(12) << Paul(x, 1e-10)
            << setw(12) << Harry(x, 1e-10) << endl;
    }


}