# Enter your code here. Read input from STDIN. Print output to STDOUT
t=int(raw_input())
for i in range(t):
    x=[]
    y=[]
    l=[]
    u=True
    n=int(raw_input())
    for j in range(n):
        h=map(int,raw_input().split())
        l.append(h)
        x.append(h[0])
        y.append(h[1])
    xmin=min(x)
    xmax=max(x)

    ymin=min(y)
    ymax=max(y)

    for j in l:
        a=j[0]
        b=j[1]
        c=0
        d=0
        if((a==xmin)|(a==xmax)):
            if((b<=ymax)|(b>=ymin)):
                u=True
            else:
                u=False
                break
        elif((b==ymin)|(b==ymax)):
            if ((a <= xmax) | (a >= xmin)):
                u = True
            else:
                u = False
                break
        else:
            u=False
            break
    if(u==True):
        print 'YES'
    else:
        print 'NO'