# Enter your code here. Read input from STDIN. Print output to STDOUT
q = input()
l = list()
li = list()

for i in range(0,q):
    count ="NO"
    n = input()
    for j in range(0,n):
        x = raw_input()
        y = x.split()
        l.append(y)
        li.extend(y)
    m = max(li)
    for e in range(0,n):
        if ((l[e][0]==m or l[e][0]==0) or (l[e][1]==m or l[e][1]==0)):
            count = "YES"
    print(count)