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

public class Solution {
    static class Line{
        Point p[] = new Point[10];
        int pi = 0;
        int ish;
        int isv;
        
        public void reset(){
            pi = 0;
            ish = 0;
            isv = 0;
        }
        
        public Point getMinMaxX(){
            int min = Integer.MAX_VALUE;
            int max = Integer.MIN_VALUE;
            for( int i = 0; i < pi; i++ ){
                if( p[i].x > max ) max = p[i].x;
                if( p[i].x < min ) min = p[i].x;
            }
            return new Point( min, max );
        }
        public Point getMinMaxY(){
            int min = Integer.MAX_VALUE;
            int max = Integer.MIN_VALUE;
            for( int i = 0; i < pi; i++ ){
                if( p[i].y > max ) max = p[i].y;
                if( p[i].y < min ) min = p[i].y;
            }
            return new Point( min, max );
        }
    }
    static class Point{
        int x,y;
        Point(int a, int b){
            x=a;
            y=b;
        }
    }
    public static int pInLine( Point x, Line L ){
        if( L.pi == 0 ){
            L.p[L.pi] = x;
            return 1;
        }
        
        if( L.pi == 1 ){
            if( x.x == L.p[L.pi].x ){
                //horizontal
                L.ish = 1;
                L.p[L.pi++] = x;
                return 1;
            }else if( x.y == L.p[L.pi].y ){
                //vertical
                L.isv = 1;
                L.p[L.pi++] = x;
                return 1;
            }
            return 0;
        }
        
        if( L.isv == 1 ){
            if( x.y == L.p[0].y ){
                L.p[L.pi++] = x;
                return 1;
            }
        }else{
            if( x.x == L.p[0].x ){
                L.p[L.pi++] = x;
                return 1;
            }
        }
        return 0;
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        
        int Q = in.nextInt();
        for( int qi = 0; qi < Q; qi++){
            
            int N = in.nextInt();
            
            Point L[] = new Point[N];
            int tx,ty,bx,by;
            tx = bx = in.nextInt();
            ty = by = in.nextInt();
            L[0] = new Point(tx,ty);
            for( int i = 1; i < N; i++){
                int x = in.nextInt();
                int y = in.nextInt();
                L[i] = new Point(x,y);
                if( tx > x ) tx = x;
                if( ty > y ) ty = y;
                if( bx < x ) bx = x;
                if( by < y ) by = y;
            }
            
            if( N < 3 ) {
                System.out.println("YES");
                continue;
            }
            
            boolean no = false;
            for( Point p : L ){
                if( p.x == tx ){
                    if((p.y < ty)||(p.y>by)){
                        System.out.println("NO");
                        no = true;
                        break;
                    }

                }else if( p.x == bx ){
                    if((p.y < ty)||(p.y>by)){
                        System.out.println("NO");
                        no = true;
                        break;
                    }
                    
                }else if( p.y == ty ){
                    if((p.x < tx)||(p.x>bx)){
                        System.out.println("NO");
                        no = true;
                        break;
                    }
                    
                }else if( p.y == by ){
                    if((p.x < tx)||(p.x>bx)){
                        System.out.println("NO");
                        no = true;
                        break;
                    }
                    
                }else{
                    System.out.println("NO");
                        no = true;
                        break;
                }
            }
            if( no ) continue;
            
            System.out.println("YES");
        }
    }
}