import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Solution {

    /// GENERIC PART

    public static void main(String[] args) throws IOException {
        init(System.in);
        solve();
    }

    private static BufferedReader reader;
    private static StringTokenizer tokenizer;

    private static void init(InputStream input) {
        reader = new BufferedReader(new InputStreamReader(input));
        tokenizer = new StringTokenizer("");
    }

    private static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    private static int nextInt() throws IOException {
        return Integer.parseInt(next(), 10);
    }

    private static int nextInt(int radix) throws IOException {
        return Integer.parseInt(next(), radix);
    }

    private static int[] nextInts(int n) throws IOException {
        final int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = nextInt();
        }
        return a;
    }

    private static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    /// SOLUTION PART

    private static void solve() throws IOException {
        int q = nextInt(), n, t1, t2;
        int g[][];
        query:
        while (q-- != 0) {

            n = nextInt();
            g = new int[n][2];
            for (int i = 0; i < n; i++) {
                t1 = nextInt();
                t2 = nextInt();
                g[i][0] = t1;
                g[i][1] = t2;
            }

            int minx = Integer.MAX_VALUE;
            int miny = Integer.MAX_VALUE;
            int maxx = Integer.MIN_VALUE;
            int maxy = Integer.MIN_VALUE;

            for (int i = 0; i < n; i++) {
                if (g[i][0] > maxx) maxx = g[i][0];
                if (g[i][0] < minx) minx = g[i][0];
                if (g[i][1] > maxy) maxy = g[i][1];
                if (g[i][1] < miny) miny = g[i][1];
            }
            for (int i = 0; i < n; i++) {
                if (!(g[i][0] == minx || g[i][0] == maxx) &&
                    !(g[i][1] == miny || g[i][1] == maxy)) {
                    System.out.println("NO");
                    continue query;
                }
            }

            System.out.println("YES");
        }
    }


}