vou chorar

//Слава Україні, Героям слава

#include <bits/stdc++.h>

using namespace std;

const int N = 1e3 + 7;

bool pode[N][N][4], vis[N][N];

// 0 -> up, 1 -> down, 2 -> left, 3 -> right
int dx[] = {0, 0, -1, 1};
int dy[] = {1, -1, 0, 0};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    memset(pode, true, sizeof(pode));
    int n;
    cin >> n;
    n++;
    vector<pair<int, int>> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i].first >> v[i].second;
    }
    for(int i = 0; i < n - 1; i++) {
        if(v[i].second == v[i + 1].second) {
            for(int x = min(v[i].first, v[i + 1].first) + 1; x <= max(v[i].first, v[i + 1].first); x++) {
                pode[x][v[i].second][0] = false;
                pode[x][v[i].second + 1][1] = false;
            }
        } else {
            for(int y = min(v[i].second, v[i + 1].second) + 1; y <= max(v[i].second, v[i + 1].second); y++) {
                pode[v[i].first][y][3] = false;
                pode[v[i].first + 1][y][2] = false;
            }
        }
    }
    int ans = 0;
    for(int i = 0; i <= 1000; i++) {
        for(int j = 0; j <= 1000; j++) {
            if(!vis[i][j]) {
                queue<pair<int, int>> q;
                vis[i][j] = true;
                q.push({i, j});
                int cnt = 0;
                while(!q.empty()) {
                    auto p = q.front(); q.pop();
                    cnt++;
                    for(int k = 0; k < 4; k++) {
                        int x = p.first + dx[k];
                        int y = p.second + dy[k];
                        if(x >= 0 and x < N and y >= 0 and y < N and !vis[x][y] and pode[p.first][p.second][k]) {
                            vis[x][y] = true;
                            q.push({x, y});
                        }
                    }
                }
                if(i) {
                    ans = max(ans, cnt);
                }
            }
        }
    }
    cout << ans << "\n";
    return 0;
}