#include
using namespace std;
int main() {
int x1, x2, y1, y2;
cin >> x1 >> y1 >> x2 >> y2;
if ((x1 > 0 && y1 > 0) && (x2 > 0 && y2 > 0)) {
cout << "YES";<br>} else if ((x1 < 0 && y1 < 0) && (x2 < 0 && y2 < 0)) {
cout << "YES";<br>} else if ((x1 > 0 && y1 < 0) && (x2 > 0 && y2 < 0)) {
cout << "YES";<br>} else if ((x1 < 0 && y1 > 0) && (x2 < 0 && y2 > 0)) {
cout << "YES";<br>} else {
cout << "NO";<br>}
}