#include<bits/stdc++.h>
using namespace std;
int a[10];
int b[10];
int main() {
	int i,x,y;
	for(i = 1; i <= 4; i++) {
		cin>>a[i]>>b[i];
	}
	if(a[1] == a[2]) {
		x = abs(b[1] - b[2]);
	} else if(a[1] == a[3]) {
		x = abs(b[1] - b[3]);
	}else if(a[1] == a[4]) {
		x = abs(b[1] - b[4]);
	}

	if(b[1] == b[2]) {
		y = abs(a[1] - a[2]);
	} else if(b[1] == b[3]) {
		y = abs(a[1] - a[3]);
	} else if(b[1] == b[4]) {
		y = abs(a[1] - a[4]);
	}

	cout<<x * y <<endl;
}
/*
 a[1] b[1]
 a[2] b[2]
 a[3] b[3]
 a[4] b[4]
*/

/**************************************************************
	Problem: 1573
	User: admin
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/