for _ in range(int(input())):
    n = int(input())
    x = []
    y = []

    for t in range(n):
        a,b = (int(p) for p in input().split())
        x.append(a)
        y.append(b)


    maxx = max(x)
    maxy = max(y)
    minx = min(x)
    miny = min(y)

    formable = True
    for i in range(n):
        if x[i] == maxx or x[i] == minx:
            continue
        if y[i] != maxy:
            formable = False
            break

    if formable:
        print("YES")
    else:
        print("NO")