#include <bits/stdc++.h> #define maxn 2001 #define maxm 500001 #define infinity ll(1e9 + 7) #define effective \ ios::sync_with_stdio(0); \ cin.tie(0); \ cout.tie(0); using namespace std; typedef long long ll; int a[maxn][maxn], cnt = 0, n; int dx[] = { 1, -1, 0, 0 }; int dy[] = { 0, 0, 1, -1 }; int od[2001 * 2001]; int odd[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 }; void enter() { int n, x, y, u, v; cin >> n; memset(a, 0, sizeof a); for (int i = 1; i <= n; i++) { cin >> x >> y >> u >> v; x += 1000, y += 1000, v += 1000, u += 1000; if (x == u) { if (y > v) swap(y, v); a[x][y] |= 1 << 2; a[x][v] |= 1 << 3; for (int j = y + 1; j < v; j++) a[x][j] |= (1 << 2) | (1 << 3); } else { if (x > u) swap(x, u); a[x][y] |= 1 << 0; a[u][y] |= 1 << 1; for (int j = x + 1; j < u; j++) a[j][y] |= (1 << 0) | (1 << 1); } } } void dfs(int x, int y) { od[cnt] += odd[a[x][y]]; a[x][y] |= cnt << 4; for (int h = 0; h < 4; h++) { if (a[x][y] & (1 << h)) { int xx = x + dx[h], yy = y + dy[h]; if (xx >= 0 && xx <= 2000 && yy >= 0 && yy <= 2000 && (a[xx][yy] >> 4) == 0) dfs(xx, yy); } } } void solve() { memset(od, 0, sizeof od); for (int x = 0; x <= 2000; x++) for (int y = 0; y <= 2000; y++) if (a[x][y] != 0 && (a[x][y] >> 4 == 0)) { cnt++; dfs(x, y); } int res = 0; for (int c = 1; c <= cnt; c++) if (!od[c]) res++; else res += od[c] / 2; cout << res; } int main() { effective; enter(); solve(); }