#include<iostream>
#include<cstdlib>
using namespace std;

int main()
{
	int x, y, x2, y2;
	cin >> x >> y >> x2 >> y2;
	if (abs(x) == abs(y)) {
		if (abs(x2) == abs(y2)) {
			if (x > x2) {
				cout << x + 1 << endl;
			}
			else {
				cout << x << endl;
			}
		}
		else {
			cout << x << endl;
		}
	}
	else if (x > y) {
		cout << x << endl;
	}
	else {
		cout << y << endl;
	}
	return 0;
}