#include <cassert>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <cmath>

using namespace std;

// to be integrated function
double f(double x) {
   return 4 / (1 + x*x);
}

// numerical integration according to the Simpson rule
// for f over the interval [a,b] using n subintervals
double simpson(double (*f)(double), double a, double b, int n) {
   assert(n > 0 && a <= b);
   double value = f(a)/2 + f(b)/2;
   double xleft;
   double x = a;
   double sum = 0;
#pragma omp parallel for \
      private(xleft) \
      lastprivate(x) \
      reduction(+:sum)
   for (int i = 1; i < n; ++i) {
      xleft = a + (i-1) * (b - a) / n;
      x = a + i * (b - a) / n;
      sum += f(x) + 2 * f((xleft + x)/2);
   }
   value += sum;
   value += 2 * f((x + b)/2);
   value *= (b - a) / n / 3;
   return value;
}

char* cmdname;
void usage() {
   cerr << "Usage: " << cmdname << " [# intervals]" << endl;
   exit(1);
}

int main(int argc, char** argv) {
   const double a = 0;
   const double b = 1;
   int N = 10000;

   cmdname = *argv++; --argc;
   if (argc > 0) {
      istringstream arg(*argv++); --argc;
      if (!(arg >> N) || N <= 0) usage();
   }
   if (argc > 0) usage();

   double sum = simpson(f, a, b, N);
   cout << setprecision(14) << sum << endl;
   cout << setprecision(14) << M_PI << endl;
}