#include "resistors.h"

void computeResistance( istream& in, ostream& out )

{

    double resistance;
    double R1;
    double R2;
    double R3;
    in >> R1;
    in >> R2;
    in >> R3;

    while( !in.fail() )

    {
        resistance = 1/(1/R1+1/R2+1/R3);

        if (R1 == 0 || R2 == 0 || R3 == 0)
        {
            out << "--error--" << endl;
            return;
        }

        out << resistance << endl;

        in >> R1;
        in >> R2;
        in >> R3;

    }


}