#include<bits/stdc++.h>
using namespace std;
const int MAX=10;
#define int long long
int n,m,ans;
struct node{
    int x,y;
} a[MAX];
inline int read(){
	int x=0,f=1;char c=getchar();
	while(c>'9'||c<'0'){if(c=='-')f=-1;c=getchar();}
	while(c<='9'&&c>='0'){x=(x<<3)+(x<<1)+(c^48);c=getchar();}
	return x*f;
}
signed main(){
    n=read();
    for(int i=1;i<=n;++i)  a[i]={read(),read()};
    n=a[3].x-a[1].x;m=a[2].y-a[1].y;
    // ans=n*(n+1)/2*m*(m+1)/2;
    // m=min(n,m);
    for(int i=1;i<=n;++i)
        for(int j=0;i+j<=m&&i+j<=n;++j){
            ans+=(n-i-j+1)*(m-i-j+1);
            // cout<<i<<" "<<j<<endl;
        }
    cout<<ans;
}