for q in range(int(input())):
    n = int(input())
    ptos = []
    esquinas = None
    for i in range(n):
        ptos.append([int(x) for x in input().split()])
        if esquinas == None:
            esquinas = [list(ptos[-1]),list(ptos[-1])]
        else:
            esquinas[0][0]=min(esquinas[0][0],ptos[-1][0])
            esquinas[0][1]=min(esquinas[0][1],ptos[-1][1])
            esquinas[1][0]=max(esquinas[1][0],ptos[-1][0])
            esquinas[1][1]=max(esquinas[1][1],ptos[-1][1])
    for pto in ptos:
        #arriba y abajo
        if esquinas[0][0]<=pto[0]<=esquinas[1][0] and (pto[1]==esquinas[0][1] or pto[1]==esquinas[1][1]):
            continue
        #lados
        if esquinas[0][1]<=pto[1]<=esquinas[1][1] and (pto[0]==esquinas[0][0] or pto[0]==esquinas[1][0]):
            continue
        print("NO")
        break
    else:
        print("YES")