# Enter your code here. Read input from STDIN. Print output to STDOUT
q=int(raw_input())
for i in xrange(q):
    n=int(raw_input())
    x,y=[],[]
    for j in xrange(n):
        l=map(int,raw_input().split())
        x.append(l[0])
        y.append(l[1])
    x0,y0=min(x+y),max(x+y)
    flag=1
    for j in xrange(n):
        if x[j]==x0 or x[j]==y0 or y[j]==x0 or y[j]==y0:
            flag=0
        else:
            flag=1
            print 'NO'
            break;
    if flag==0:
        print 'YES'