#include <algorithm>
#include <cstdio>
using i32 = int;
constexpr i32 N = 5000;
i32 n, a0, b0;
i32 L[N + 1], R[N + 1];
signed main() noexcept {
	scanf("%d%d%d", &n, &a0, &b0);
	for (i32 i = 0; i <= n; ++i) R[i] = -n, L[i] = n;
	L[0] = R[0] = b0;
	for (i32 i = 1, al, ar, bl, br; i <= n; ++i) {
		scanf("%d%d%d%d", &al, &ar, &bl, &br);
		for (i32 j = i; ~j; --j)
			if (al <= j + a0 && j + a0 <= ar) {
				i32 l = std::max(L[j], bl), r = std::min(R[j], br);
				if (l <= r)
					R[j] = std::max(R[j], r + 1), L[j + 1] = std::min(L[j + 1], l), R[j + 1] = std::max(R[j + 1], r);
			}
	}
	i32 ans = 0;
	for (i32 i = 0; i <= n; ++i) ans = std::max(ans, i + R[i] - b0);
	printf("%d\n", ans);
	return 0;
}