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

public class Solution {

    public static void main(String[] args) throws IOException{
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        
        int T = Integer.parseInt(br.readLine());
        
        while(T-->0) {
            int q = Integer.parseInt(br.readLine());
            boolean bad = false;
            ArrayList<int[]> A = new ArrayList<>();

            for(int i=0;i<q;i++) {
                long x = -1;
                long y = -1;
                String[] in = br.readLine().split(" ");
                int[] a = {Integer.parseInt(in[0]),Integer.parseInt(in[1])};
                if(i==0) {
                    A.add(a);
                    continue;
                }
                boolean seen = false;
                for(int j = 0;j<A.size();j++) {
                    int[] p = {A.get(j)[0], A.get(j)[1]};

                    if(bad) break;
                    if(p[1] == a[1]) {
                        if(x==-1) {
                            x = (long) Math.pow((p[0]-a[0]), 2);
                            seen=true;
                        }
                        else {
                            long dist = (long) Math.pow((p[0]-a[0]), 2);
                            if(dist <= x) seen=true;
                            else {
                                //bad
                            }
                        }
                    }
                    else if(p[0] == a[0]) {
                        if(y==-1) {
                            y = (long) Math.pow((p[1]-a[1]), 2);
                            seen=true;
                        }else{
                            long dist = (long) Math.pow((p[1]-a[1]), 2);
                            if(dist <= y) seen=true;
                            else {
                                //bad
                            }
                        }
                    }
                    else {
                        
                    }
                    
                }
                if(seen) A.add(a);
                if(!seen) bad = true;

            }
            if(bad) {
                bw.append("NO\n");
            }
            else {
                bw.append("YES\n");
            }
        }
        bw.close();
    }
}