Problem:
 Score : 100 points    Problem Statement There are H rows and W columns of white square cells.  You will choose h of the rows and w of the columns, and paint all of the cells contained in those rows or columns.  How many white cells will remain?  It can be proved that this count does not depend on what rows and columns are chosen.      Constraints  All values in input are integers.  1 \leq H, W \leq 20  1 \leq h \leq H  1 \leq w \leq W         Input Input is given from Standard Input in the following format:  H  W  h  w       Output Print the number of white cells that will remain.        Sample Input 1 3 2
2 1      Sample Output 1 1  There are 3 rows and 2 columns of cells. When two rows and one column are chosen and painted in black, there is always one white cell that remains.       Sample Input 2 5 5
2 3      Sample Output 2 6       Sample Input 3 2 4
2 4      Sample Output 3 0

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

ans=H*W-(h*W+(H-h)*w)
print(ans)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print(H*W - h*W - H*w + h*w)

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
hh,ww = map(int, input().split())
h, w = map(int, input().split())
s = hh*ww - h*ww - hh*w + h*w
print(s)

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H - h) * (W - w))

Solution (Python):

area_h, area_w = map(int, input().split())
h, w = map(int, input().split())
print((area_h - h)*(area_w - w))

Solution (Python):
a=list(map(int,input().split()))
b=list(map(int,input().split()))
print((a[0]-b[0])*(a[1]-b[1]))

Solution (Python):
(H,W)=(int(i) for i in input().split())
(h,w)=(int(i) for i in input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

whole = H*W
points_row = h * W
points_column = w * H
duplicates = h * w

print(whole - (points_row + points_column - duplicates))

Solution (Python):
a=list(map(int,input().split()))
b=list(map(int,input().split()))
print((a[0]-b[0])*(a[1]-b[1]))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print( H* W - (H * w + h * W - h * w))

Solution (Python):
H1, W1 = map(int,input().split())
h2, w2 = map(int,input().split())

print((H1-h2) * (W1-w2))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

print(H*W-h*W-H*w+h*w)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H*W)-(h*W)-((w*H-h*w)))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
h, w = list(map(int, input().split()))
r, c = list(map(int, input().split()))
print((h - r) * (w - c))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = H*W - (h*W+w*H-h*w)
print(ans)

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

Solution (Python):

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
v=h*w
print(H*W-(h*W+w*H-v))

Solution (Python):

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
white=H*W-h*W-w*H+h*w
print(white)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
answer = (H - h) * (W - w)
print(answer)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
f = lambda x,y:x-y if x>y else 0
print(f(H, h)*f(W, w))

Solution (Python):
def main():

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

if __name__ == "__main__":
    main()

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

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

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

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print(max(H*W-h*W-w*H+h*w,0))

Solution (Python):
h,w=map(int,input().split())
x,y=map(int,input().split())
print((h-x)*(w-y))

Solution (Python):
h, w = map(int, input().split())
sh, sw = map(int, input().split())

print((h - sh) * (w - sw))

Solution (Python):
H,W = [int(x) for x in input().split()]
h,w = [int(x) for x in input().split()]
print((H-h)*(W-w))

Solution (Python):
a, b = map(int, input().split())
c, d = map(int, input().split())
print (((a - c) * (b - d)))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
n = h*W+w*(H-h)
print(H*W-n)

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print((H*W)-((H*w)+(W*h)-(h*w)))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
h,w= map(int,input().split())
a,b= map(int,input().split())
print(h*w-a*w-b*h+a*b)

Solution (Python):
H,W,h,w=map(int,open(0).read().split())
print((W-w)*(H-h))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = (H - h) * (W - w)
print(ans)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h) * (W-w))

Solution (Python):
h,w=map(int,input().split())
x,y=map(int,input().split())
print((h-x)*(w-y))

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
A = H * W - h * W - w * H + h * w
print(A)

Solution (Python):
def main():
    H, W = [int(i) for i in input().split()]
    h, w = [int(i) for i in input().split()]
    print((H-h)*(W-w))


if __name__ == "__main__":
    main()

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print (H * W - h * W - H * w + h * w)

Solution (Python):
length, width = input().split()
length, width = int(length),int(width)
x, y = input().split()
x,y = int(x),int(y)
 
print((length-x) * (width-y))

Solution (Python):
a,b = [int(i) for i in input().split()]

c,d = [int(i) for i in input().split()]

print((a-c)*(b-d))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h) * (W-w))

Solution (Python):

A,B=map(int,input().split())
a,b=map(int,input().split())
print((A-a)*(B-b))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((W-w)*(H-h))

Solution (Python):
H, W=map(int, input().split())
h, w=map(int, input().split())

print(H*W-h*W-H*w+h*w)

Solution (Python):
import sys

if sys.platform =='ios':
    sys.stdin=open('input_file.txt')
    
    
H,W=map(int,input().split())
h,w=map(int,input().split())

print(H*W-h*W-H*w+w*h)

Solution (Python):
List=[list(map(int,input().split())) for i in range(2)]
H=List[0][0]
W=List[0][1]
h=List[1][0]
w=List[1][1]
white=H*W-h*W-H*w+h*w
print(white)

Solution (Python):
H,W = [int(x) for x in input().split()]
h,w = [int(x) for x in input().split()]
print(H*W-h*W-(w*(H-h)))

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

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

Solution (Python):
A = list(map(int, input().split()))
B = list(map(int, input().split()))
print((A[0]-B[0])*(A[1]-B[1]))

Solution (Python):
H, W = list(map(int,input().split()))
h, w = list(map(int,input().split()))

Hh = H -h
Ww = W - w
print(Hh * Ww)

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

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H*W) - (h*W) - (w*(H-h)))

Solution (Python):
if __name__ == '__main__':
    H, W = map(int, input().split())
    h, w = map(int, input().split())
    
    print(H*W - W*h - (H-h)*w)

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())


print(H*W - h*W - w*H + h*w)

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h) * (W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
s=list(input().split())
t=list(input().split())
sa=int(s[0])
sb=int(s[1])
ta=int(t[0])
tb=int(t[1])

total=sa*sb
leave=total-(ta*sb+tb*(sa-ta))

print(leave)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):

import sys
def input():
	return sys.stdin.readline().strip()

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

print((H - h)*(W - w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H, W = list(map(int, input().split()))
h, w = list(map(int, input().split()))

ans = (H - h) * (W - w)
print(ans)

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

Solution (Python):
H,W=input().split()
print(eval('('+H+'-'+input().replace(' ',')*('+W+'-')+')'))

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

Solution (Python):
X,Y = [int(i) for i in input().split()]
x,y = [int(i) for i in input().split()]
print(X*Y - (x*Y + y*(X-x)))

Solution (Python):
a,b = map(int, input().split())
c,d = map(int, input().split())
print((a-c)*(b-d))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
ans = (H-h)*(W-w)
print(ans)

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

Solution (Python):
import sys
input=sys.stdin.readline

def main():
    H,W = map(int,input().split())
    h,w = map(int,input().split())
    print(H*W -h*W -w*(H-h))

if __name__ == '__main__':
    main()

Solution (Python):
a = list(map(int,input().split()))
b = list(map(int,input().split()))

print( a[0]*a[1]-(a[0]*b[1] + a[1]*b[0] -b[0]*b[1]))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print(H*W-(H*w+W*h-h*w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
total = H * W
print(total - h*W - w*H + h*w)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
h, w = map(int, input().split())
hh, ww = map(int, input().split())
print(h * w - hh * w - h * ww + hh * ww)

Solution (Python):
import sys

H,W = map(int,input().split())
h,w = map(int,input().split())

print(H*W-h*W-w*H+h*w)

Solution (Python):
def makelist(n, m):
    return [[0 for i in range(m)] for j in range(n)]

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

Solution (Python):
def MAP(): return list(map(int,input().split()))

H,W = MAP()
h,w = MAP()

print(H*W-(h*W+w*H)+h*w)

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print(H*W-((h*W)+(w*H)-(h*w)))

Solution (Python):
H,W,h,w=map(int,open(0).read().split());print((H-h)*(W-w))

Solution (Python):
a,b=map(int,input().split())
aa,bb=map(int,input().split())
aaa=a-aa
bbb=b-bb
print(int(aaa*bbb))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

s=(H-h)*(W-w)

print(s)

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

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

Solution (Python):

a,b = map(int,input().split())
c,d = map(int,input().split())
print(a*b-c*b-a*d+c*d)

Solution (Python):


def main():
    H,W = map(int, input().split())
    h, w = map(int, input().split())

    return H * W - h * W - w * H + h * w
    
if __name__ == '__main__':
    print(main())

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

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

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())

print(H * W - h * W - w * H + h * w)

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H,W=map(int, input().split())
h,w=map(int, input().split())
print((H-h)*(W-w))

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

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print(H*W - W*h - (H-h)*w)

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

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

white = 0
for i in range(1,H+1):
    if i <= h:
        continue
    for j in range(1,W+1):
        if j <= w:
            continue
        white +=1
print(white)

Solution (Python):
h,w=map(int,input().split())
a,b=map(int,input().split())
print((h-a)*(w-b))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H - h) * (W - w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H, W = map(int, input().split(" "))
h, w = map(int, input().split(" "))

print(H * W + h * w - H * w - h * W)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H - h) * (W - w))

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H - h) * (W - w))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())

print(max((H-h)*(W-w),0))

Solution (Python):
def main():
    H, W = map(int, input().split())
    h, w = map(int, input().split())

    print((H-h)*(W-w))

main()

Solution (Python):
def inpl(): return list(map(int, input().split()))

H,W = inpl()
h,w = inpl()

print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print(H*W-(H*w+W*h-h*w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
a,b = map(int,input().split())
c,d = map(int,input().split())

print((a-c)*(b-d))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print(int((H - h) * (W - w)))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H - h) * (W - w))

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

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h) * (W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = (H-h) * (W-w)
print(ans)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
import numpy as np

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

mtx = np.ones([H, W])

mtx[:h] = 0
mtx[:, 0:w] = 0

print(np.count_nonzero(mtx))

Solution (Python):

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

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

Solution (Python):
import sys
input = sys.stdin.readline

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

zen = H * W
kuro = h * W + w * H - w * h

print(zen - kuro)

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

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

ans=(H - h)*(W-w)
print(ans)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

all_cell = H * W
black_cell = h * W + w * H - w * h

print(all_cell - black_cell)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((W - w) * (H - h))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
a,b=map(int,input().split())
c,d=map(int,input().split())
print((a-c)*(b-d))

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

ans = (H-h)*(W-w)
print(ans)

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
def main():
  H, W = map(int, input().split())
  h, w = map(int, input().split())
  
  print((H-h)*(W-w))

if __name__ == "__main__":
  main()

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
def resolve():
    H,W = map(int,input().split())
    Hs,Ws = map(int,input().split())
    ans = H*W
    ans -= Hs*W
    ans -= Ws*(H-Hs)
    print(ans)
resolve()

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

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
a, b = map(int, input().split())
c, d = map(int, input().split())
print((a-c)*(b-d))

Solution (Python):
h,w = map(int, input().split())
y,x = map(int, input().split())
print(h*w-(y*w+x*h)+y*x)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
row, col = map(int, input().split())
nr, nc = map(int, input().split())

all = row * col
colored_row = nr * col
colored_col = nc * row
double = nr * nc

colored = all - colored_row - colored_col + double

print(colored)

Solution (Python):
h,w = map(int,input().split())
x,y = map(int,input().split())
print(h*w-x*w-y*h+x*y)

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

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

Solution (Python):
a=list(map(int,input().split()))
b=list(map(int,input().split()))
print((a[0]-b[0])*(a[1]-b[1]))

Solution (Python):

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
hi, wi = map(int, input().split())
ho, wo = map(int, input().split())

if 1 <= hi <= 20 and 1 <= wi <= 20 and 1 <= ho <= hi and 1 <= wo <= wi:
    white = hi * wi
    black = hi * wo + ho * wi - ho * wo
    print(white - black)
else:
    print('hoge')

Solution (Python):
a, b = map(int, input().split())
c, d = map(int, input().split())
print((a-c)*(b-d))

Solution (Python):
def main():
    H, W = map(int, input().split())
    h, w = map(int, input().split())
    return H*W - H*w - h*W + h*w

if __name__ == '__main__':
    print(main())

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())

P=(h*W+w*H)-h*w

print((H*W-P))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h) * (W-w))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H-h)*(W-w))

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

Solution (Python):
HW = list(map(int, input().split()))
hw = list(map(int, input().split()))
print((HW[0]-hw[0])*(HW[1]-hw[1]))

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

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print(H*W-(h*W+H*w)+h*w)

Solution (Python):
H, W=map(int, input().split())
h, w=map(int, input().split())
ans=(W-w)*(H-h)
print(ans)

Solution (Python):
a,b=map(int,input().split())
c,d=map(int,input().split())
print((a-c)*(b-d))

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

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
white=H*W
black= h*W+H*w-h*w
print(white-black)

Solution (Python):
H, W = (int(i) for i in input().split())
h, w = (int(i) for i in input().split())
ans = H * W
sel = h * W + w * (H - h)
ans -= sel
print(ans)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print(H*W-h*W-w*H+h*w)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print((H-h)*(W-w))

Solution (Python):
a,b = map(int, input().split())
c,d = map(int, input().split())
print((a-c)*(b-d))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = H * W - (h * w) - (H - h) * w - (W - w) * h
print(ans)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = (H-h)*(W-w)
print(ans)

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

Solution (Python):
hh, ww = map(int,input().split())
h, w = map(int,input().split())
print((hh-h)*(ww-w))

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

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())
print((H-h) * (W-w))

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

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

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

Solution (Python):
H,W =map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split(' '))
h, w = map(int, input().split(' '))
print((H - h) * (W - w))

Solution (Python):


H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
ans = (H-h) * (W-w)
print(ans)

Solution (Python):
H, W = list(map(int, input().split()))
h, w = list(map(int, input().split()))

print(H*W-(W*h+H*w-h*w))

Solution (Python):
a,b=map(int,input().split())
c,d=map(int,input().split())
print((a-c)*(b-d))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
a,b=map(int,input().split())
c,d=map(int,input().split())

print((a-c)*(b-d))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
A,B = map(int,input().split())
C,D = map(int,input().split())

print((A-C)*(B-D))

Solution (Python):
H,W = map(int, input().split())
h,w = map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print((H*W)-(h*W+w*H-(h*w)))

Solution (Python):
def solve():
    H, W = map(int, input().split())
    h, w = map(int, input().split())
    return (H - h) * (W - w)  


if __name__ == "__main__":
    print(solve())

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H-h)*(W-w))

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

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=input().split()
H,W=int(H),int(W)
h,w=input().split()
h,w=int(h),int(w)

print((H-h)*(W-w))

Solution (Python):
import math





inputa = input().split()
inputb = input().split()

a = int(inputa[0])
b = int(inputa[1])


x = int(inputb[0])
y = int(inputb[1])

ans = a*b - x*b - y*a + x*y
print(ans)

Solution (Python):
H,W=map(int, input().split())
h,w=map(int, input().split())
print((H-h)*(W-w))

Solution (Python):
import numpy as np

def test():
    H,W = map(int,input().split())
    h,w = map(int,input().split())

    data = np.ones((H,W))
    data[:h,:] = 0
    data[:,:w] = 0
    print(int(data.sum()))


if __name__ == "__main__":
    test()

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

area = H * W

area = area - (h * W)

if area != 0:
  H -= h
  area -= (w * H)
print(area)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

ans = (H*W) - (h*W) - (H-h)*w
print(ans)

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((W-w)*(H-h))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
H,W=map(int,input().split())
h,w=map(int,input().split())

print(H*W-H*w-h*W+h*w)

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print ((H-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
print((H - h) * (W - w))

Solution (Python):
H,W = map(int,input().split())
h,w = map(int,input().split())
print((H-h)*(W-w))

Solution (Python):
board = list(map(int,input().split()))
select = list(map(int,input().split()))

answer = (board[0]-select[0])*(board[1]-select[1])
print(answer)

Solution (Python):
H,W,h,w=map(int, open(0).read().split()); print((H-h)*(W-w))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())

print(H*W - h*W - w*H + h*w)

Solution (Python):
a, b = map(int, input().split())
c, d = map(int, input().split())

print((a * b) - (a * d) - (b * c) + (c * d))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h)*(W-w))

Solution (Python):
H, W = map(int,input().split())
h, w = map(int,input().split())

print(H*W-h*W-w*H+h*w)

Solution (Python):
H,W,h,w = map(int,open(0).read().split())
print(max(H*W-h*w-(H-h)*w-(W-w)*h,0))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())

print((H-h) * (W-w))