#include <iostream>
#include <math.h>

using namespace std;

int main(int argc, char *argv[]) {
    int input = 0, width, height, radius;
    cout << "Please enter a number 1-4: ";
    cin >> input;
    if((input > 4) || (input < 1)) {
        cout << "Error: You may not input a number greater than 4 or less than 1." << endl;
        return(1);
    }
    switch(input) {
        case 1:
            radius = 0;
            cout << "Please enter the radius of your circle: ";
            cin >> radius;
            if(radius < 1) {
                cout << "Error: You may not input a number less than 1 for the radius." << endl;
                return(2);
            }
            cout << "The area of your circle is " << 3.14159 * pow(radius, 2) << " units." << endl;
            break;
        case 2:
            width = height = 0;
            cout << "Please enter the width of your rectangle: ";
            cin >> width;
            if(width < 1) {
                cout << "Error: You may not input a number less than 1 for the width." << endl;
                return(3);
            }
            cout << "Please enter the height of your rectangle: ";
            cin >> height;
            while(height < 1) {
                cout << "Error: You may not input a number less than 1 for the height." << endl;
                return(4);
            }
            cout << "The area of your rectangle is " << width * height << " units." << endl;
            break;
        case 3:
            width = height = 0;
            cout << "Please enter the base of your rectangle: ";
            cin >> width;
            if(width < 1) {
                cout << "Error: You may not input a number less than 1 for the base." << endl;
                return(5);
            }
            cout << "Please enter the height of your rectangle: ";
            cin >> height;
            while(height < 1) {
                cout << "Error: You may not input a number less than 1 for the height." << endl;
                return(6);
            }
            cout << "The area of your rectangle is " << width * height * 0.5 << " units." << endl;
            break;
        case 4:
            return(0);
    }
}