#include <iostream>
#include <sstream>
#include <string>
using namespace std;


int main()
	{
	char vars[4]={ "a", "b", "c", "d"};
	long g, h;
	char Restart;
	const char * roman[4][3]={"I","II","III", "IV"};
	bool nFound = false;
	string str; 
	
	cout<<"Hello, welcome to Shayne's Equality Calculator!\n";
	cout<<"Imagine the equality layed out as an X Y graph,\n";
	cout<<"with each quadrant numbered 1 - 4. Please input\n";
	cout<<"the data accordingly, using x as the variable.\n\n\n";
	
	for(int x = 0; x < 4; x++) 
		{
            cout<<"Quadrant " << roman[x] <<endl;
            cin >>str;
			if(str == "x") {
				if(nFound = false)
				{
					nFound = true;
					str >> vars[x];
				}
				else
				{
					std::cout<<"Error\n";
					return 1;
				}
				}	
			else
			{
				std::istringstream istr(str);
				istr >> vars[x];

			}
		}
    
	if(nFound == true)
		{
		cout<<"\n\nError - Please make sure you are using x as your\n";
		cout<<"variable at least one time, but only one time.\n";
		goto stop;
		}
	else if (a == "x")	
		{
		g=b*d;
		h=g/c;
		
		cout << "x = " << h << endl;
		goto stop;
		}
	else if (b == "x")	
		{
		g=c*a;
		h=g/d;
				
		cout << "x = " << h << endl;
		goto stop;
		}
	else if (c == "x")	
		{
		g=d*b;
		h=g/a;
		
		cout << "x = " << h << endl;
		goto stop;
		}
	else if (d = "x")	
		{
		g=a*c;
		h=g/b;
				
		cout << "x = " << h << endl;
		goto stop;
		}

	stop:
	cout << "\n\n(r)estart, (e)xit\n";
	cin >> Restart;
	switch (Restart)
		{
		case 'r':
		system("CLS");
		return main();
		break;
			
		case 'e':
		return 0;
		break;

		default:
		printf("Invalid key: Use 'e' or 'r'\n");
		break;
		}
		return 0;   
	}