wifi.cpp

#include<bits/stdc++.h>
using namespace std;
#define tii tuple<int, int, int, int, int>
#define all(x) x.begin(), x.end()
#define pb push_back
const int maxn = 2e5+5, INF = 0x3f3f3f3f;

int calc[maxn], bit[maxn];
vector<tii> pontos;
vector<int> comp;

int pos(int x){
	int l=0, r= comp.size()-1;
	while(l<=r){
		int m = (l+r)>>1;
		if(comp[m]<x) l=m+1;
		else r = m-1;
	}

	return l+1;
}

void upd(int x){
	for(; x < maxn; x+=x&-x) bit[x]++;
}
int sum(int x){
	int rt = 0;
	for(; x > 0; x-=x&-x) rt+=bit[x];
	return rt;
}

int32_t main(){
	ios::sync_with_stdio(false); cin.tie(0);

	memset(calc, INF, sizeof calc);

	int n; cin >> n;
	for(int i = 0; i < n; i++){
		int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
		pontos.pb({x1, y2, x1, y1, i}); // inferior/superior esquerdo
		pontos.pb({x2, y1, x2, y2, i}); // superior/inferior direito
		comp.pb(y1), comp.pb(y2);
	}

	sort(all(pontos));
	sort(all(comp));
	comp.erase(unique(all(comp)), comp.end());

	int ans = 0;
	for(auto[xp, yp, xm, ym, i] : pontos){
		int val = sum(pos(yp)) - sum(pos(ym));
		
		if(calc[i]==INF) calc[i] = val;
		else{
			if(calc[i]+val==0) ans++;
			upd(pos(yp));
		}
	}

	cout << ans << '\n';
}