/** gnu specific **/
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
/** contains everything I need in std **/
#include <bits/stdc++.h>

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(S) ((int)S.size())
#define FOR(i, st_, n) for(int i = st_; i < n; ++i)
#define RFOR(i, n, end_) for(int i = (n)-1; i >= end_; --i)
#define x first
#define y second
#define pb push_back
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef unsigned long long ull;
typedef long double LD;
typedef pair<ull, ull> pull;
using namespace __gnu_pbds;
typedef tree<ll, null_type, less<>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
using namespace std;
#ifdef ONPC
mt19937 rnd(228);
#else
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
#endif

#define MAX_N 2000

int M[MAX_N][MAX_N];
int vis[MAX_N][MAX_N];

vector<pii> D = {{0,-1}, {0, 1}, {1, 0}, {-1,0}};

int unset(int num, int p)
{
	return num & (~(1 << p));
}

void unconnect(pii a, pii b)
{
	if(a.x == b.x)
	{
		for(int i = min(a.y, b.y); i < max(a.y, b.y); ++i)
		{
			if(a.x-1 >= 0)
			{
				M[a.x][i] = unset(M[a.x][i], 3);
				M[a.x-1][i] = unset(M[a.x-1][i], 2);
			}
		}
	}
	else if(a.y == b.y)
	{
		for(int i = min(a.x, b.x); i < max(a.x, b.x); ++i)
		{
			if(a.y-1 >= 0)
			{
				M[i][a.y] = unset(M[i][a.y], 0);
				M[i][a.y-1] = unset(M[i][a.y-1], 1);
			}
		}
	}
	else assert(false);
}

void dfs(pii v, int marker)
{
	queue<pii> Q;
	Q.push(v);
	vis[v.x][v.y] = marker;
	while(!Q.empty())
	{
		v = Q.front();
		Q.pop();
		auto [x, y] = v;
		FOR(i,0,sz(D))
		{
			auto [dx, dy] = D[i];
			if(((M[x][y] >> i) & 1) && x+dx >= 0 && x+dx < MAX_N && y+dy >= 0 && y+dy < MAX_N && !vis[x+dx][y+dy])
			{
				vis[x+dx][y+dy] = marker;
				Q.push({x+dx, y+dy});
			}
		}
	}

}

int solve()
{
	int n;
	if(!(cin >> n))
		return 1;
	FOR(i,0,MAX_N)
	{
		FOR(j,0,MAX_N)
		{
			M[i][j] = 0b1111;
		}
	}
	vector<pii> p(n+1);
	FOR(i,0,n+1) cin >> p[i].x >> p[i].y;

	FOR(i,0,n)
	{
		unconnect(p[i], p[i+1]);
	}
	int marker = 1;
	FOR(i,0,MAX_N)
	{
		FOR(j,0,MAX_N)
		{
			if(!vis[i][j])
			{
				dfs({i,j}, marker++);
			}
		}
	}
	vector<int> S(marker, 0);
	FOR(i,0,MAX_N)
	{
		FOR(j,0,MAX_N)
		{
			S[vis[i][j]] += 1;
		}
	}
	sort(rall(S));
	cout << S[1] << "\n";
    return 0;
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int TET = 1e9;
    //cin >> TET;
    for (int i = 1; i <= TET; i++)
    {
        if (solve())
        {
            break;
        }
#ifdef ONPC
        cout << "__________________________" << endl;
#endif
    }
#ifdef ONPC
    cerr << endl << "finished in " << clock() * 1.0 / CLOCKS_PER_SEC << " sec" << endl;
#endif
}