t= int(input())

for z in range(t):
    count = 0
    x_cord = []
    y_cord = []
    q=int(input())
    arr = []
    for x in range(q):
        arr_t = [int(i) for i in input().split()]
        arr.append(arr_t)
    for x in range(q):
        x_cord.append(arr[x][0])
    for y in range(q):
        y_cord.append(arr[y][1])    
    #print(x_cord)
    #print(y_cord)
    min_x = min(x_cord)
    min_y = min(y_cord)
    max_x = max(x_cord)
    max_y = max(y_cord)
    #print(min_x,min_y,max_x,max_y)
    for x in range(q):
        if(arr[x][0]==min_x or arr[x][1]==min_y or arr[x][0]==max_x or arr[x][1]==max_y):
            count+=1
            #print("count",count)        
    if(count==q):
        print("YES")
    else:
        print("NO")