#include <bits/stdc++.h>

#define _ << " " <<
#define tr(x) cout << #x _ x << endl
#define fi first
#define se second

#ifdef _WIN32
#define LD "%I64d"
#else
#define LD "%ld"
#endif

using namespace std;

typedef long long ll;

struct Point {
    int x, y;
    Point (int x, int y) : x(x), y(y) {
    }
};

bool cmpX(const Point & a, const Point & b) {
    if (a.x == b.x) 
        return a.y < b.y;
    return a.x < b.x;
}

bool cmpY(const Point & a, const Point & b) {
    if (a.y == b.y)
        return a.x < b.x;
    return a.y < b.y;
}

int n;

vector<Point> pts;

int read() {
    if (scanf("%d", &n) < 1) {
        return 0;
    }
    pts.clear();
    int x, y;
    for (int i = 0; i < n; i++) {
        scanf("%d%d", &x, &y);
        pts.push_back(Point(x, y));
    }
    return 1;
}

void solve() {
    if (n == 1) {
        printf("YES\n");
        return ;
    }
    if (n == 2) {
        if (pts[0].x == pts[1].x || pts[0].y == pts[1].y) {
            printf("YES\n");
        }
        else {
            printf("NO\n");
        }
        return ;
    }
    int minx = (int) 1e8, maxx = - (int) 1e8;
    int miny = (int) 1e8, maxy = - (int) 1e8;
    for (int i = 0; i < n; i++) {
        if (minx > pts[i].x) minx = pts[i].x;
        if (maxx < pts[i].x) maxx = pts[i].x;
        if (miny > pts[i].y) miny = pts[i].y;
        if (maxy < pts[i].y) maxy = pts[i].y;
    }
    sort(pts.begin(), pts.end(), cmpX);
    assert(pts[0].x == minx && pts[n - 1].x == maxx);
    int oy = (int) 1e8;
    for (int i = 1; i < n - 1; i++) {
        if (oy == (int) 1e8) {
            oy = pts[i].y;
        }
        else if (oy != pts[i].y && minx != pts[i].x && maxx != pts[i].x) {
            printf("NO\n");
            return ;
        }
    }
    sort(pts.begin(), pts.end(), cmpY);
    assert(pts[0].y == miny && pts[n - 1].y == maxy);
    int ox = (int) 1e8;
    for (int i = 1; i < n - 1; i++) {
        if (ox == (int) 1e8) {
            ox = pts[i].x;
        }
        else if (ox != pts[i].x && miny != pts[i].y && maxy != pts[i].y) {
            printf("NO\n");
            return ;
        }
    }
    printf("YES\n");
}

int q;

int main(int argc, char *argv[]) {
    scanf("%d", &q);
    while (q-- && read()) {
        solve();
    }
}