set可以快速的插入和删除
#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <queue>
#include <algorithm>
#include <set>
using namespace std;
const int maxn = 1e5+10;
multiset<int> s;
multiset<int> :: iterator it;
struct node {
int x,y;
node(int a=0,int b=0):x(a),y(b){}
bool operator < (const node &rhs) {
return x < rhs.x;
}
}a[maxn],b[maxn];
int main() {
int t,n;
scanf ("%d",&t);
while(t--) {
s.clear();
scanf ("%d",&n);
for (int i = 1; i <= n; i++) scanf ("%d%d",&a[i].x,&a[i].y);
for (int i = 1; i <= n; i++) scanf ("%d%d",&b[i].x,&b[i].y);
sort(a+1,a+1+n);
sort(b+1,b+1+n);
int j = 1,ans = 0;
for (int i = 1; i <= n; i++) {
while(j <= n && b[j].x <= a[i].x) { s.insert(b[j].y); j++; }
it = s.upper_bound(a[i].y);
if (s.size() != 0 && it != s.begin()) it--;
if (s.size() > 0 && (*it) <= a[i].y) {
ans++;
s.erase(it);
}
}
cout << ans << endl;
}
return 0;
}