#include <iostream.h>


int main () {

  int reply, resistor_count;
  double value, sum_of_inverses;

  do {

    resistor_count = 0;
    sum_of_inverses = 0;

    cout << endl << "Enter resistance value (-ve to end list): ";
    cin >> value;

    while (value > 0) {

      sum_of_inverses = sum_of_inverses + (1 / value);
      resistor_count = resistor_count + 1;

      cout << "Enter resistance value (-ve to end list): ";
      cin >> value;

    }

    if (value < 0) { // we stopped because of a negative value

      if (resistor_count == 0) {

        cout << endl << "The resistance is infinite." << endl;

      } else {

        cout << endl
             << "The total resistance is " << 1 / sum_of_inverses << endl;

      }

    } else { // we stopped because a zero resistance was entered

      cout << endl << "There is no point in entering any further values."
           << endl << "The total resistance is zero." << endl;
           
    }

    cout << endl
         << "Enter a value greater than zero to continue, anything else to stop: ";
    cin >> reply;

  } while (reply > 0);

}