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

long long A, B, C, D;
unsigned long long VA, VB, VC, VD;
int ty1, ty2;

int sgn(long long val) {
	if (val < 0LL) return -1;
	if (val > 0LL) return 1;
	return 0;
}

int main() {
	cin >> A >> B >> C >> D;
	assert(-4000000000LL <= A && A <= 4000000000LL);
	assert(-4000000000LL <= B && B <= 4000000000LL && B != 0LL);
	assert(-4000000000LL <= C && C <= 4000000000LL);
	assert(-4000000000LL <= D && D <= 4000000000LL && D != 0LL);
	VA = (unsigned long long)abs(A);
	VB = (unsigned long long)abs(B);
	VC = (unsigned long long)abs(C);
	VD = (unsigned long long)abs(D);

	// A/B の正負を判定
	if (sgn(A) == 0) ty1 = 0;
	else if (sgn(A) + sgn(B) == 0) ty1 = -1;
	else ty1 = 1;

	// C/D の正負を判定
	if (sgn(C) == 0) ty2 = 0;
	else if (sgn(C) + sgn(D) == 0) ty2 = -1;
	else ty2 = 1;

	// 場合分け
	if (ty1 < ty2) { cout << "Yes" << endl; }
	else if (ty1 > ty2) { cout << "No" << endl; }
	else if (ty1 == 0) { cout << "No" << endl; }
	else if (ty1 == -1) {
		if (VA * VD > VB* VC) cout << "Yes" << endl;
		else cout << "No" << endl;
	}
	else if (ty1 == 1) {
		if (VA * VD < VB * VC) cout << "Yes" << endl;
		else cout << "No" << endl;
	}
	return 0;
}