#include <bits/stdc++.h>

#define rep(i, n)   for(int i=0;i<n;i++)

using namespace std;

typedef pair<int, int>pii;

int solve(vector<pii>vec){
    int n = vec.size();
	bool flag = true;
	int X = 1e9, Y = -1e9;
	sort(vec.begin(), vec.end());
	rep(i, n){
		if(vec[i].first == vec[0].first) X = min(X, vec[i].second), Y = max(Y, vec[i].second);
		if(vec[i].first == vec[n-1].first) X = min(X, vec[i].second), Y = max(Y, vec[i].second);
	}
    set<int>s1, s2;
	rep(i, n){
		if(vec[i].first == vec[0].first) continue;
		if(vec[i].first == vec[n-1].first) continue;
		if(vec[i].second < Y && vec[i].second > X) flag = false;
	    if(vec[i].second < X) s1.insert(vec[i].second);
        if(vec[i].second > Y) s2.insert(vec[i].second);
    }
    flag &= s1.size() <= 1;
    flag &= s2.size() <= 1;
	return flag;
}

int main() {
    int n, m, q,x, y;
    cin >> q;
    while(q--){
        cin >> n;
        vector<pii>vec;
        rep(i, n){
            cin >> x >> y;
            vec.push_back(pii(x, y));
        }
        sort(vec.begin(), vec.end());
        int flag = solve(vec);
        rep(i, n) swap(vec[i].first, vec[i].second);
        flag &= solve(vec);
        if(flag) cout << "YES\n";
        else cout << "NO\n";
    }
    return 0;
}