#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=15;
const int inf=1e18;
int n,mnx=inf,mny=inf,mxx=-inf,mxy=-inf,res,x[N],y[N];
double S,eps=1e-5;
double gets(double a,double b,double c){
	double k=(a+b+c)/2;
	return sqrtl(k*(k-a)*(k-b)*(k-c));
}
double d(int x1,int y1,int x2,int y2){
	return sqrtl((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
bool in(int xx,int xy){
	double ans=0;
	for(int i=2;i<=n;i++){
		ans+=gets(d(xx,xy,x[i-1],y[i-1]),d(xx,xy,x[i],y[i]),d(x[i-1],y[i-1],x[i],y[i]));
	}
	ans+=gets(d(xx,xy,x[1],y[1]),d(xx,xy,x[n],y[n]),d(x[1],y[1],x[n],y[n]));
	return abs(ans-S)<=eps;
}
signed main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>x[i]>>y[i];
	}
	for(int i=3;i<=n;i++){
		S+=gets(d(x[1],y[1],x[i],y[i]),d(x[1],y[1],x[i-1],y[i-1]),d(x[i],y[i],x[i-1],y[i-1]));
	}
	int res=0;
	for(int i=0;i<=20;i++){
		for(int j=0;j<=20;j++){
			for(int k=0;k<i;k++){
				for(int t=j+1;t<=20;t++){
					int a=t-j,b=i-k;
					if(in(i,j)&&in(k,t)&&in(i-a,j-b)&&in(k-a,t-b))res++;
				}
			}
			for(int k=i-1;k>=0;k--){
				int a=i-k;
				if(in(k,j-a)&&in(i,j)&&in(k,j)&&in(i,j-a))res++;
			}
		//	cout<<i<<" "<<j<<" "<<in(i,j)<<endl;
		}
	}
	cout<<res;
}