q = int(input())
for k in range(q):
    n = int(input())
    x=[]
    y=[]
    cx,cy=0,0
    for i in range(n):
        a,b = input().strip().split(' ')
        a,b = int(a),int(b)
        x.append(a)
        y.append(b)

    min_x = min(x)
    min_y = min(y)
    mx = max(x)
    my = max(y)

    for i in range(len(x)):
        if(x[i]!=min_x and x[i]!=mx):
            if(y[i]==min_y or y[i]==my):
                cx=cx
            else:
                cx+=1
                break
        if(y[i]!=min_y and y[i]!=my):
            if(x[i]==min_x or x[i]==mx):
                cy=cy
            else:
                cy+=1
                break

    if(cx==0 and cy==0):
        print("YES")
    else:
        print("NO")