n=int(input())
for i in range(n):
    xpoints=[]
    flag=True
    ypoints=[]
    x1=[]
    arr=[]
    y1=[]
    q=int(input())
    for j in range(q):
        
        x,y=[int(_) for _ in input().split()]
        arr.append((x,y))
        x1.append(x)
        y1.append(y)
        
    
    xmin=min(x1)
    xmax=max(x1)
    ymin=min(y1)
    ymax=max(y1)
    
    for j in arr:
#       print(j)
        if j[0]!=xmin and j[0]!=xmax and j[1]!=ymin and j[1]!=ymax: flag=False
#    print(xmin,xmax,ymin,ymax)
    if flag:
        print("YES")
    else:print("NO")