import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int Q = in.nextInt();
        for(int q = 0; q<Q; q++) {
            int n = in.nextInt();
            int arr[][] = new int[n][2];
            int maxRow = -1000000;
            int maxCol = -1000000;
            int minRow = 1000000;
            int minCol = 1000000;
            boolean isPossible = true;
            for(int i = 0; i<n; i++) {
                int row = in.nextInt();
                int col = in.nextInt();
                arr[i][0] = row;
                arr[i][1] = col;
                if(row>maxRow) {
                    maxRow = row;
                }
                if(col>maxCol) {
                    maxCol = col;
                }
                if(row<minRow) {
                    minRow = row;
                }
                if(col<minCol) {
                    minCol = col;
                }
            }
            for(int i = 0; i<n; i++) {
                int row = arr[i][0];
                int col = arr[i][1];
                if(row>minRow && row<maxRow && col>minCol && col<maxCol) {
                    isPossible = false;
                    break;
                }
            }
            if(isPossible) {
                System.out.println("YES");
            } else {
                System.out.println("NO");
            }
        }
    }
}