#include<bits/stdc++.h>
using namespace std;
#define read(st,en,a) for(int II=st;II<=en;II++) cin>>a[II]
#define up(s,e,i) for(int i=s;i<=e;i++)
#define down(s,e,i) for(int i=s;i>=e;i--) 
#define all(x) x.begin(),x.end()
#define endl '\n' 
#define int long long

namespace Main
{
    const int N = 10;
    const double eps = 1e-6;
    int n;
    pair<int, int> p[N];
    bool in(int x,int y)
    {
        int u = 0, d = 0;
        up(1,n,i)
        {
            int x1 = p[i].first, y1 = p[i].second, x2 = p[i % n + 1].first,
                y2 = p[i % n + 1].second;
            if(x1>x2)
                swap(x1, x2), swap(y1, y2);
            if(x<x1||x>x2)
                continue;
            double k = (y1 - y2) * 1.0 / (x1 - x2)*1.0, b = y1 - k * x1;
            double pt = k * x + b;
            if(fabs(y-pt)<=eps)
                return 1;
            else if(y<pt)
                u = 1;
            else
                d = 1;
        }
        return u && d;
    }
    bool isin[2010][2010];

    pair<int,int> get(int x)
    {
        pair<int, int> ans;
        ans.first = 0x3f3f3f3f3f3f3f3f;
        ans.second = -0x3f3f3f3f3f3f3f3f;
        up(1,n,i)
        {
            int x1 = p[i].first, y1 = p[i].second, x2 = p[i % n + 1].first,
                y2 = p[i % n + 1].second;
            if(x1>x2)
                swap(x1, x2), swap(y1, y2);
            if(x<x1||x>x2)
                continue;
            if(x1==x2)
                continue;
            double k = (y1 - y2) * 1.0 / (x1 - x2)*1.0, b = y1 - k * x1;
            double pt = k * x + b;
            
            if(ceil(pt)-pt<=eps)
                pt = ceil(pt);
            if(pt-floor(pt)<=eps)
                pt = floor(pt);
            ans.first = min(ans.first,(int)ceil(pt));
            ans.second = max(ans.second,(int)floor(pt));
        }
        return ans;
    }
    int f[2010], g[2010];

    void main()
    {
        ios::sync_with_stdio(0);
        cin.tie(0);cout.tie(0);
        cin >> n;
        up(1, n, i) cin >> p[i].first >> p[i].second;
        int ans = 0;
        up(0, 2000, i) f[i] = get(i).first, g[i] = get(i).second;
        up(0,2000,k) up(1,2000,i) up(0,2000-i-k,j)
        {
            int d = max({f[k], f[k + i] + j, f[k + j] - i, f[k + i + j] + j - i});
            int u = min({g[k], g[k + i] + j, g[k + j] - i, g[k + i + j] + j - i});
            ans += max(0ll, u - d + 1);
        }
        cout << ans;
    }
};

signed main()
{
    Main::main();
    return 0;
}