q = int(input().strip())
while q > 0:
    n = int(input().strip())
    plusPetitX = float('inf')
    plusPetitY = float('inf')
    plusGrandX = -float('inf')
    plusGrandY = -float('inf')
    l = []
    possible = True
    for n0 in range(n):
        x,y = [int(i) for i in input().strip().split(" ")]
        if x < plusPetitX :
            plusPetitX = x
        if x > plusGrandX :
            plusGrandX = x
        if y < plusPetitY:
            plusPetitY = y
        if y > plusGrandY:
            plusGrandY = y
        l.append((x,y))
    for pair in l:
        if (pair[0] != plusPetitX and pair[0] != plusGrandX) and pair[1] != plusPetitY and pair[1] != plusGrandY:
            possible = False
            break
            
              
        
    
        
    if possible:
        print("YES")
    else:
        print("NO")
    q -= 1