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

public class Solution {

    public static void main(String[] args) throws Exception{
        /* 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));
        int t = Integer.parseInt(br.readLine());
        for(int r=0;r<t;r++){
            int q = Integer.parseInt(br.readLine());
            ArrayList<String>al= new ArrayList<String>();
            for(int y=0;y<q;y++){
                String s= br.readLine();;
                al.add(s);
            }
            ArrayList<Float>slope= new ArrayList<Float>();
            for(int i=0;i<al.size();i++){
                String s1[]= al.get(i).split(" ");
                float x1 = Float.parseFloat(s1[0]);
                float y1 = Float.parseFloat(s1[1]);
                for(int j=i+1;j<al.size();j++){
                    String s2[]= al.get(j).split(" ");
                     float x2 = Float.parseFloat(s2[0]);
                     float y2 = Float.parseFloat(s2[1]);
                    if(x2-x1!=0)
                        slope.add((y2-y1)/(x2-x1));
                    else
                        slope.add(Float.MAX_VALUE);
                }
            }
            boolean flag=true;
            for(int i=0;i<slope.size();i++){
                
                float f = slope.get(i);
                for(int j=i+1;j<slope.size();j++){
                    float g = slope.get(j);
                    if(f*g==-1 || f==g  || (f==Float.MAX_VALUE && g == 0) || (g==Float.MAX_VALUE && f == 0)){
                      //   System.out.println(f+" "+g);
                    }
                    else{
                     //  System.out.println(f+" "+g);
                        flag = false;
                        break;
                    }
                }
                if(!flag)
                    break;
            }
            if(flag)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}