// sum of volume and mass of spheres
#include <iostream>
#include <math.h>
using namespace std;

namespace sphere
{
  double volume(double r)
  {
    const double pi = 3.1416;
    return 4./3. * pi * pow(r, 3.);
  }
  
  double mass(double r, double rho)
  {
    return rho * volume(r); 
  }
}

const double r1=1., r2=3.; // radii of spheres 
const double rho=7.87; // density

int main()  
{  
  using namespace sphere;

  double volume_sum = volume(r1) + volume(r2); // sphere:: omitted 
  cout << volume_sum << endl; // total volume

  double mass_sum = mass(r1, rho) + mass(r2, rho);
  cout << mass_sum << endl;  // total mass
}