#include <iostream>
#include <cstddef>
#include <math.h>
#include <iomanip>

//poznaz v 13

double EPSILON = 1 * 10e-15;

double actg(double x) {
    if (fabs(x) > 1.0) return 0.;
    double part = -x;
    double n = 1.;
    double sum = M_PI / 2.;
    double delta = part;
    while (fabs(delta) > EPSILON) {
        delta = sum;
        sum += part / n;
        delta -= sum;
        part *= x * x * -1.;
        n += 2.;
    }
    return sum;
}

int main() {
    int k;
    std::cout << "beware! k > 9 requires a lot of time." << std::endl;
    std::cout << "k = ";
    std::cin >> k;
    EPSILON = pow(10, -k);
    double step;
    std::cout << "step = ";
    std::cin >> step;
    double x = -1;
    while (fabs(x) <= 1) {
        double r = actg(x);
        double e = M_PI / 2. - atan(x);
        std::cout << std::setprecision(k) << r << "       " << e << "       " << fabs(e - r) << std::endl;
        x += step;
    }
    return 0;
}