# Enter your code here. Read input from STDIN. Print output to STDOUT
q = int(raw_input())
while q:
    n = int(raw_input())
    b = 'YES'
    xg,yg = 0,0
    while n and (b == 'YES'):
        x,y = map(int,raw_input().split(' '))
        if max(x,y) < max(xg,yg):
            b = 'NO'
        xg,yg = max(x,y),max(x,y)
        n -= 1
    print b
    q -= 1