#include <iostream>
using namespace std;
int main ()
{
int x, x2, y, y2;
cin>>x>>y>>x2>>y2;
if (x>0 && x2>0 && y>0 && y2>0 || x>0 && x2>0 && y<0 && y2<0 || x<0 && x2<0 && y>0 && y2>0 || x<0 && x2<0 && y<0 && y2<0)
cout<<"YES";
else
cout<<"NO";
return 0;
}
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