package main
import "fmt"

type Point struct {
	x int
	y int
}

func readInput(pointsNumber int) []Point {
	points := make([]Point, pointsNumber)
	var x_value,y_value int
	for i := 0; i<pointsNumber; i++ {
		fmt.Scanf("%d", &x_value)
		fmt.Scanf("%d", &y_value)
		point := Point{
			x:x_value,
			y:y_value,
		}
		points[i] = point
	}
	return points
}

func findMinMaxCoordinates(points []Point) (int, int, int, int) {
	var minX, maxX, minY, maxY int
	minX = points[0].x
	maxX = points[0].x
	minY = points[0].y
	maxY = points[0].y
	for _, point := range points {
		if maxX < point.x {
			maxX = point.x
		}
		if minX > point.x {
			minX = point.x
		}
		if maxY < point.y {
			maxY = point.y
		}
		if minY > point.y {
			minY = point.y
		}
	}
	return minX, maxX, minY, maxY
}

func doPointsFit(points []Point, minX, maxX, minY, maxY int) bool {
	for _, point := range points {
		if !(point.x == minX || point.x == maxX || point.y == minY || point.y == maxY) {
			return false
		}
	}
	return true
}

func main() {
	var test, pointNumber int
	fmt.Scanf("%d", &test)
	for i:=0; i<test; i++ {
		fmt.Scanf("%d", &pointNumber)
		points := readInput(pointNumber)
		minX, maxX, minY, maxY := findMinMaxCoordinates(points)
		result := doPointsFit(points, minX, maxX, minY, maxY)
		if result {
			fmt.Println("YES")
		} else {
			fmt.Println("NO")
		}
	}
}