# Enter your code here. Read input from STDIN. Print output to STDOUT
import sys
LINES = sys.stdin.readlines()
Q = int(LINES[0])
cur_line = 1

def solve(pts):
    xmi = 100000
    xma = -100000
    ymi = 100000
    yma = -100000

    for (x,y) in pts:
        xmi = min(xmi, x)
        xma = max(xma, x)
        ymi = min(ymi, y)
        yma = max(yma, y)
    #print 
    for (x,y) in pts:
        #print (x,y), xmi,xma,ymi,yma
        #print "(%s == %s or %s == %s)" % (x,xmi,x,xma)
        #print "(%s == %s or %s == %s)" % (y,ymi,y,yma)
        if (x == xmi or x == xma):
            continue
        if (y == ymi or y == yma):
            continue
        return False
    return True
    
    
for q in xrange(Q):
    N = int(LINES[cur_line])
    cur_line += 1
    pts = []
    for n in xrange(N):
        x,y = map(int, LINES[cur_line].split())
        cur_line += 1
        pts.append((x,y))
    print "YES" if solve(pts) else "NO"