#include <iostream>
#include <vector>

using namespace std;

int main()
{
	
	int t;
	cin >> t;
	while (t--)
	{
        bool check = false;
        int Array[10000][10000];
        int xsmall = 0;
        int ysmall = 0;
        int xbig = 0;
        int ybig = 0;
        
		int quer;
		cin >> quer;
		for (int i = 0; i < quer; i++)
		{
			int x,y;
            cin >> x >> y;
            Array[x][y]++;
            if(x < xsmall)
                xsmall = x;
            else if(x > xbig)
                xbig = x;
                
           if(y < ysmall)
                xsmall = x;
            else if(y > ybig)
                ybig = y;  
                
           

		}
        
        for(int i = 0; i < xbig; i++){
            for(int j = 0; j < ybig;j++){
                if(Array[i][j] != 0)
                    check = false;
            }
        }
        
        if(check == true)
            cout << "YES\n";
        else
            cout << "NO\n";
	}
}