#include <iostream>
#include <string>

using namespace std;

int main ()
{
    string InputString;
    cout << "What to solve for: (E/I/R): ";
    getline (cin, InputString, '\n');
    double iVoltage, iAmperage, iResistance;
    switch (InputString[0])
    {
    case ('e'):
    case ('E'):
        cout << "\nSelected Voltage.";
        cout << "\nAmperage:\t";
        cin >> iAmperage;
        cout << "\nResistance:\t";
        cin >> iResistance;
        cout << "\nVoltage: " << iAmperage*iResistance;
        getline (cin, InputString, '\n');
        break;

    case ('i'):
    case ('I'):
        cout << "\nSelected Amperage.";
        cout << "\nVoltage:\t";
        cin >> iVoltage;
        cout << "Resistance\t";
        cin >> iResistance;
        cout << "\nAmperage: " << iVoltage/iResistance;
        break;

    case ('r'):
    case ('R'):
        cout << "\nSelected Resistance.";
        cout << "\nVoltage:\t";
        cin >> iVoltage;
        cout << "\nAmperage:\t";
        cin >> iAmperage;
        cout << "\nResistance: " << iVoltage/iAmperage;
        break;
    }

    getline (cin, InputString, '\n');
    return 0;
}