# Enter your code here. Read input from STDIN. Print output to STDOUT

for _ in xrange(int(raw_input())):
    n = int(raw_input())
    p = []
    x1,y1 = 10**9,10**9
    x2,y2 = -10**9,-10**9
    for _ in xrange(n):
        x,y = map(int,raw_input().split())
        p.append([x,y])
        x1 = min(x,x1)
        y1 = min(y,y1)
        x2 = max(x,x2)
        y2 = max(y,y2)

    for i in xrange(n):
        if p[i][0] == x1 or p[i][0] == x2:
            if p[i][1] >= y1 and p[i][1] <= y2:
                a = 0
            else:
                a = 1
                break
        elif p[i][1] == y1 or p[i][1] == y2:
            if p[i][0] >= x1 and p[i][0] <= x2:
                a = 0
            else:
                a = 1
                break
        else:
            a = 1
            break

    if a == 0:
        print 'YES'
    else:
        print 'NO'