import numpy as np

H,W = list(map(int, input().split()))

h,w = list(map(int, input().split()))

matrix = [[1 if (i>w-1 and j>h-1) else 0 for i in range(W)] for j in range(H)]

print((np.sum(matrix)))
H, W = list(map(int, input().split()))

h, w = list(map(int, input().split()))



print((H*W - W*h - H*w + h*w))
import numpy as np

H, W = list(map(int, input().split()))
h, w = list(map(int, input().split()))
matrix = [[1 if (i > w - 1 and j > h - 1) else 0 for i in range(W)] for j in range(H)]
print((np.sum(matrix)))

H, W = list(map(int, input().split()))
h, w = list(map(int, input().split()))
print((H * W - W * h - H * w + h * w))

-import numpy as np - -matrix = [[1 if (i > w - 1 and j > h - 1) else 0 for i in range(W)] for j in range(H)] -print((np.sum(matrix))) +print((H * W - W * h - H * w + h * w))