#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using u64=unsigned long long;
//using lll=__int128_t;
using lf=long double;
using Pr=pair<int,int>;
#define F(i,l,r) for(ll i=l;i<=ll(r);++i)
#define G(i,r,l) for(ll i=r;i>=ll(l);--i)
#define ct const
#define il inline
#define pb push_back
#define fi first
#define se second
#define mkr make_pair
template<class T>
il void tomn(T&x,T ct&y){y<x?x=y,0:0;}
template<class T>
il void tomx(T&x,T ct&y){x<y?x=y,0:0;}
#define dbg(...) fprintf(stderr,__VA_ARGS__)
#define CUT dbg("===================\n")
ct lf EPS=1e-10L;
il int dcmp(lf x){return fabs(x)<=EPS?0:(x<0?-1:1);}
ct ll INF=4e18L;
//ct int INF=1.02e9;
//il void rd(int&x){scanf("%d",&x);}
//il void rd(ll&x){scanf("%lld",&x);}

ct ll P=1000000007;
void add2(ll&x,ll y){x+=y,x-=((-(x>=P))&P);}
void sub2(ll&x,ll y){x-=y,x+=((-(x<0))&P);}
ll add(ll x,ll y){return add2(x,y),x;}
ll sub(ll x,ll y){return sub2(x,y),x;}

struct Vec{ll x,y;};
Vec operator-(Vec x,Vec y){return Vec{x.x-y.x,x.y-y.y};}
ll cross(Vec x,Vec y){return x.x*y.y-x.y*y.x;}

ct int N=10,M=55;
int n;
bool mp[M][M];
Vec p[N];
bool insi(Vec x){
	F(i,1,n)if(cross(p[i]-p[i-1],x-p[i-1])>0)return 0;
	return 1;
}
bool ck(int x,int y){return 0<=x&&x<M&&0<=y&&y<M&&mp[x][y];}
int main(){
#ifdef LOCAL
	freopen("B.in","r",stdin);
//	freopen(".out","w",stdout);
#endif
	scanf("%d",&n);
	F(i,1,n)scanf("%lld%lld",&p[i].x,&p[i].y);
	p[0]=p[n];
	F(x,0,M-1)F(y,0,M-1)mp[x][y]=insi(Vec{x,y});
	int ans=0;
	F(x,0,M-1)F(y,0,M-1)if(ck(x,y))F(i,1,M-1)F(j,0,M-1)
		ans+=ck(x+i,y+j)&&ck(x+i-j,y+i+j)&&ck(x-j,y+i);
	printf("%d\n",ans);
}