#include <stdio.h>
#include <windows.h>
#include <iostream>

using namespace std;

int main()
{
	double a1, b1, c1;
	double a2, b2, c2;

	cout << "input a1: ";
	cin >> a1;
	cout << "input b1: ";
	cin >> b1;
	cout << "input c1: ";
	cin >> c1;
	cout << "input a2: ";
	cin >> a2;
	cout << "input b2: ";
	cin >> b2;
	cout << "input c2: ";
	cin >> c2;


	double x, y;

	if (((a1 != 0) || (b1 != 0)) && ((a2 != 0) || (b2 != 0))) {
		if ((a1 == a2) && (b1 == b2) && (c1 == c2))
			cout << "lines coincide" << endl;

		else if ((a1 == a2) && (b1 == b2) && (c1 != c2))
			cout << "lines don't overlap" << endl;

		else {
			y = (c2 - (a2 * c1 / a1)) / ((((-(a2)) * c1) / a1) + b2);
			x = (c1 - b1 * y) / a1;
			cout << "lines ovelap: ";
			cout << "x = " << x << ", y = " << y << endl;
		}
	}
	else if (((a1 == 0) && (b1 == 0)) && ((a2 != 0) || (b2 != 0)))
		cout << "first line doesn't exist" << endl;

	else if (((a2 != 0) || (b2 != 0)) && ((a1 == 0) && (b1 == 0)))
		cout << "second line doesn't exist" << endl;

	else if ((a2 == 0) && (b2 == 0) && (a1 == 0) && (b1 == 0))
		cout << "both lines don't exist" << endl;
	else cout << "wrong input" <<

	system("pause");