#include <iostream>
using namespace std;
double solution1(double v, double r1, double r2, double r3) {
  double r = 1.0 / (1.0 / r1 + 1.0 / r2 + 1.0 / r3);
  return v / r;
}
double solution2(double v, double r1, double r2, double r3) {
  return v / r1 + v / r2 + v / r3;
}
int main() {
  double r1 = 10.0, r2 = 20.0, r3 = 30.0; // set resistance
  double v0 = 6.0; // set voltage

  cout << solution1(v0, r1, r2, r3) << endl;
  cout << solution2(v0, r1, r2, r3) << endl;
  return 0;
}
/* end */

1.1
1.1