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

int main() {
	int n, a, b, c, a1 = 0;
	cin >> n >> a >> b >> c;
	if (a == b) {
		a1 = n + c;
	}
	if (a != b && a != 0 && b != 0) {
		a1 = n - c / 4;
	}
	if (a == 0) {
		a1 = n;
	}
	if (a1 > 0) {
		cout << a1;
	} else if (a1 <= 0) {
		cout << "0";
	}
	return 0;
}
language