#include<bits/stdc++.h>
#define int long long
using namespace std;
int t,a,b,c,d,Mx=-1e9,mx=1e9,My=-1e9,my=1e9;
signed main(){
	cin>>t;
	while(t--){
		cin>>a>>b>>c>>d;
		Mx=max(Mx,max(a,c));
		mx=min(mx,max(a,c));
		My=max(My,min(b,d));
		my=min(my,min(b,d));
	}
	printf("%lld\n",abs((Mx-mx)*(My-my)));
	return 0;
}