queries = int(input())
for i in range(queries):
    minX = 10000
    maxX = -10000
    minY = 10000
    maxY = -10000
    pts = int(input())
    points = []
    for p in range(pts):
        coords = [int(x) for x in input().split(' ')]
        points.append(coords)
        if coords[0] > maxX:
            maxX = coords[0]
        elif coords[0] < minX:
            minX = coords[0]
            
        if coords[1] > maxY:
            maxY = coords[1]
        elif coords[1] < minY:
            minY = coords[1]
    res = "YES"
    bounds = [minY,maxY,minX,maxX]
    for point in points:
        if minX <= point[0] <= maxX:
            if point[1] == minY or point[1] == maxY:
                continue
            elif point[0] == minX or point[0] == maxX:
                continue
            else:
                res = "NO"
        if minY <= point[1] <= maxY:
            if point[0] == minX or point[0] == maxX:
                continue
            elif point[1] == minY or point[1] == maxY:
                continue
            else:
                res = "NO"
               
    print(res)