import java.util.;
public class Main {
public static void main(String args[]) {
Scanner in=new Scanner(System.in);
int N=in.nextInt();
int a[]=new int[N];
int b[]=new int[N];
for(int i=0;i<N;i++)
{
a[i]=in.nextInt();
b[i]=in.nextInt();
}
int gap1,gap2;
int min1 = a[0];
int max1 = a[0];
for (int i = 0; i < N; i++)
{
if (a[i] > max1)
max1 = a[i];
if (a[i] < min1)
min1 = a[i];
}
gap1=Math.abs(min1 - max1);
min1 = b[0];
max1 = b[0];
for (int i = 0; i < N; i++)
{
if (b[i] > max1)
max1 = b[i];
if (b[i] < min1)
min1 = b[i];
}
gap2=Math.abs(min1 - max1);
//System.out.println(gap1+" "+gap2);
long area=(gap1-2)(gap2-2);
System.out.print(area);
}
}