import java.util.Scanner;

public class RectanglePoints {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int q = s.nextInt();
        int x1=0,y1=0,x2=0,y2=0,flagx = 0,flagy = 0;
        for (int i = 0; i < q; i++) {
            int n = s.nextInt();
            int flag = 0;
            for (int j = 0; j < n; j++) {
                int a = s.nextInt();
                int b = s.nextInt();
                if(j==0){
                    x1 = a;
                    y1 = b;
                }
                else {
                    if(flagx==0 && flagy==0){
                        if(x1!=a){
                            x2 = a;
                            flagx = 1;
                        }
                        if(y1!=b){
                            y2 = b;
                            flagy = 1;
                        }
                        continue;
                    }
                    if(flagx==0 && flagy==1){
                        if(x1!=a){
                            x2 = a;
                            flagx = 1;
                            if(!(b>=Math.min(y1, y2) && b<=Math.max(y1, y2))){
                                flag=1;
                                break;
                            }
                        }
                        continue;
                    }
                    if(flagx==1 && flagy==0){
                        if(y1!=b){
                            y2 = b;
                            flagy = 1;
                            if(!(a>=Math.min(x1, x2) && a<=Math.max(x1, x2))){
                                flag=1;
                                break;
                            }
                        }
                        continue;
                    }
                    if(flagx==1 && flagy==1){
                        if(!((a==x1 || a==x2)&&(b>=Math.min(y1, y2) && b<=Math.max(y1, y2))) && 
                           !((b==y1 || b==y2)&&(a>=Math.min(x1, x2) && a<=Math.max(x1, x2)))){
                            flag = 1;
                            break;
                        }
                    }
                }
            }
            if(flag==0)System.out.println("YES");
            else {
                System.out.println("NO");
            }
        }
    }
}