nq = int(input().strip())
for q in range(nq):
    np = int(input().strip())
    p = [tuple(int(x) for x in input().strip().split()) for i in range(np)]
    x0,x1 = min(x for x,y in p), max(x for x,y in p)
    y0,y1 = min(y for x,y in p), max(y for x,y in p)
    result = "YES"
    for x,y in p:
        if x == x0 or x == x1 or y == y0 or y== y1:
            continue
        else:
            result = "NO"
            break
    print(result)