#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <utility>
using namespace std;


int main() {
    int q;
    scanf("%d", &q);
    while (q--) {
        int n;
        scanf("%d", &n);
        vector<pair<int, int>> pt(n);
        for (auto &x : pt) scanf("%d %d", &x.first, &x.second);
        int minx = 100000, maxx = -100000;
        for (auto x : pt) {
            minx = min(minx, x.first);
            maxx = max(maxx, x.first);
        }
        if (minx == maxx) {
            printf("YES\n");
            continue;
        }
        vector<int> diffy1, diffy2;
        for (auto x : pt) {
            if (x.first != minx && x.first != maxx)
                diffy1.push_back(x.second);
            else diffy2.push_back(x.second);
        }
        sort(diffy1.begin(), diffy1.end());
        diffy1.erase(unique(diffy1.begin(), diffy1.end()), diffy1.end());
        if (diffy1.size() > 2) {
            printf("NO\n");
            continue;
        }
        int miny = *min_element(diffy2.begin(), diffy2.end());
        int maxy = *max_element(diffy2.begin(), diffy2.end());
        if (diffy1.size() == 0) {
            printf("YES\n");
        } else if (diffy1.size() == 1) {
            if (miny >= diffy1[0] || maxy <= diffy1[0]) printf("YES\n");
            else printf("NO\n");
        } else {
            if (miny >= diffy1[0] && maxy <= diffy1[1]) printf("YES\n");
            else printf("NO\n");
        }
    }
    return 0;
}