t = int(input())
for _t in range(t):
    n = int(input())
    al = []
    bl = []
    maxa = -999999
    maxb = -999999
    mina = 999999
    minb = 999999
    for _n in range(n):
        a, b = map(int, input().split())
        al.append(a)
        bl.append(b)
        maxa = max(maxa, a)
        mina = min(mina, a)
        maxb = max(maxb, b)
        minb = max(minb, b)
    possible = True
    for _n in range(n):
        if al[_n] != maxa and al[_n] != mina and bl[_n] != maxb and bl[_n] != minb:
            possible = False
    print('YES' if possible else 'NO')