Q=int(input())
for q in range(Q):
    N=int(input())
    s=[]
    x_val=[]
    y_val=[]
    for n in range(N):
        x,y=[int(i) for i in input().split()]
        s+=[(x,y)]
        x_val+=[x]
        y_val+=[y]
    x_val.sort()
    y_val.sort()
    for i in s:
        if i[0] not in [x_val[0],x_val[-1]] and i[1] not in [y_val[0],y_val[-1]]:
            print("NO")
            break
    else:
        print("YES")