q=int(input())
for _ in range(q):
    n=int(input())
    x=[]
    y=[]
    f=0
    for i in range(n):
        t1,t2=[int(i) for i in input().split()]
        x.append(t1)
        y.append(t2)
    x1,x2=min(x),max(x)
    y1,y2=min(y),max(y)
    for i in range(n):
        c=0
        if(y1<=y[i]<=y2 and (x[i]==x1 or x[i]==x2)):
            c=1
        elif(x1<=x[i]<=x2 and(y[i]==y1 or y[i]==y2)):
            c=1
        else:
            c=0
        if(c==0):
            f=1
            print('NO')
            break
    if(f==0):
        print('YES')