import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) 
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(n>0)
        {
            int flag=0;
            int m = sc.nextInt();
            for(int i=0;i<m;i++)
            {
                int x = sc.nextInt();
                int y = sc.nextInt();
                if((x!=0 || y!=0) || (x!=(n-1) || y!=(n-1)))
                {
                    
                }
                else
                {
                    flag=1;
                }
            }
            if(flag==1)
            {
                System.out.println("NO");
            }
            else
            {
                System.out.println("YES");
            }
            n--;
        }
    }
}