#include <iostream>
#include <cstring>
#include <cstdio>
#include <set>
#include <vector>

const int N = 5e3 + 10;
int n, a, b, ans;
bool vis[N][N];
std::set < int > s[N];
std::vector < int > tmp;

void ins (int x, int y) {
	ans = std::max(ans, x + y - a - b);
	if (vis[x - a][y - b]) return ;
	vis[x - a][y - b] = true;
	if (!vis[x - a + 1][y - b] || !vis[x - a][y - b + 1]) s[x - a].insert(y);
}

int main() {
	std::cin >> n >> a >> b;
	vis[0][0] = 1;
	s[a].insert(b);
	for (int i = 1, la, ra, lb, rb; i <= n; i++) {
		std::cin >> la >> ra >> lb >> rb;
		la = std::max(la - a, 0);
		ra = std::min(ra - a, i - 1);
		for (int j = la; j <= ra; j++) {
			tmp.clear();
			std::set < int >::iterator it = s[j].lower_bound(lb);
			for ( ; it != s[j].end() && (*it) <= rb; it++)
				tmp.push_back(*it);
			for (auto v : tmp) {
				s[j].erase(v);
				ins(j + a + 1, v);
				ins(j + a, v + 1); 
			}
		}
	}
	std::cout << ans;
	return 0;
}