Box 1
x - y = 4
x - 0 = 4
x = 4
Box 2
y = 0
(x, y) => (4, 0)
Box 3
-1 - y = 4
-y = 4 + 1
y = -5
Box 4
x = 0
y = -4
(x, y) => (0, -4)
