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())
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())

H -= h
W -= w

print(H*W)

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

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

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

main()

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())
a=H-h
b=W-w
print(a*b)

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

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-H*w + h*w)

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

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

print(Area)

Solution (Python):
HW = [int(i) for i in input().split()]
hw = [int(i) for i in input().split()]

print((HW[0] - hw[0])*(HW[1] - hw[1]))

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, raw_input().split(' '))
h,w = map(int, raw_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):
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 = map(int, input().split())
h, w = map(int, input().split())

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

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


if __name__ == '__main__':
    main()

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

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


if __name__ == '__main__':
    solve()

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

print((M - m) * (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-h)*(W-w))

Solution (Python):
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline

input_n = lambda: int(readline())
input_nn = lambda: map(int, readline().split())
input_s = lambda: readline().rstrip().decode('utf-8')
input_ss = lambda: readline().rstrip().decode('utf-8').split()


def main():
    H, W = input_nn()
    h, w = input_nn()
    ans = H * W - (H * w + W * h - h * w)
    print(ans)


if __name__ == '__main__':
    main()

Solution (Python):

h, w, x, y = map(int, open(0).read().split())
print((h-x)*(w-y))

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

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

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

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-a) * (w-b))

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 math
def ip():return int(input())
def inp():return map(int,input().split())

H,W=inp()
h,w=inp()
print((H-h)*(W-w))

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

if '__main__' == __name__:
    resolve()

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())

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

hyo = H * W
hr = h * W
wr = w * (H-h)

ans = (hyo - (hr+wr))
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):
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())
hh,ww = map(int, input().split())
print((h-hh) * (w-ww))

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

Solution (Python):






from collections import deque



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())
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 = [input().split() for l in range(2)]
a = (int)(h[0][0])
b = (int)(h[1][0])
c = (int)(h[0][1])
d = (int)(h[1][1])
ans = (a - b) * (c - d)
print(ans)

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

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())

all_cells = (H * W)
checked_as_row = (W * h)
checked_as_col = (H * w)
duplicated_check = (h * w)


rest_cells = all_cells - checked_as_row - checked_as_col + duplicated_check

print(rest_cells)

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()))
dh, dw = list(map(int, input().split()))

print((h-dh) * (w-dw))

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

Solution (Python):
h_1, w_1 = map(int, input().split())
h_2, w_2 = map(int, input().split())

print((h_1 - h_2)*(w_1 - w_2))

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

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

print(A)

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
black=h*W+w*H-h*w
print(white-black)

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

Solution (Python):
import bisect,collections,copy,heapq,itertools,math,string
import sys
def S(): return sys.stdin.readline().rstrip()
def M(): return map(int,sys.stdin.readline().rstrip().split())
def I(): return int(sys.stdin.readline().rstrip())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())
H, W = M()
h, w = M()
print((H-h)*(W-w))

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 = 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())
a,b = map(int,input().split())

print(h*w - a*w - b*h + a*b)

Solution (Python):
import sys
H, W = map(int, sys.stdin.readline().rstrip().split())
h, w = map(int, sys.stdin.readline().rstrip().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):
from collections import defaultdict, deque
import sys

INF = float('inf')
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def I(): return int(sys.stdin.buffer.readline())
def LS(): return sys.stdin.buffer.readline().rstrip().decode('utf-8').split()
def S(): return sys.stdin.buffer.readline().rstrip().decode('utf-8')
def IR(n): return [I() for i in range(n)]
def LIR(n): return [LI() for i in range(n)]
def SR(n): return [S() for i in range(n)]
def LSR(n): return [LS() for i in range(n)]
def SRL(n): return [list(S()) for i in range(n)]
def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]


h1, w1 = LI()
h, w = LI()
ans = max(0, (h1 - h) * (w1 - 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())

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

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

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

H = H - h
W = W -w

print(H*W)

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

Solution (Python):
x = [list(map(int,input().split())) for i in range(2)]
print((x[1][1]-x[0][1])*(x[1][0]-x[0][0]))

Solution (Python):
def main():
  NUM=list(map(int,input().split()))
  H=NUM[0]
  W=NUM[1]
  num=list(map(int,input().split()))
  h=num[0]
  w=num[1]
  print(H*W-(h*W)-(H*w)+w*h)

main()

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*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-h)*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):
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
E = h * W
K = w * H
O = h * w
print((N - (E + K))+O)

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_1, w_1 = map(int, input().split())
h_2, w_2 = map(int, input().split())

ans = (h_1 - h_2) * (w_1 - w_2)
print(ans)

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

a = h*W
b = H*w
c = h*w

print(H*W - (a+b-c))

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

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

Solution (Python):
hh, ww = [int(i) for i in input().split()]
h, w = [int(i) for i in input().split()]
print(hh * ww - h * ww - hh * w + h * w)

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

Solution (Python):
import re
n = input()
n1 = input()
m = re.search('(\d+)\s(\d+)', n)
m1 = re.search('(\d+)\s(\d+)', n1)
a = int(m.group(1))
b = int(m.group(2))
c = int(m1.group(1))
d = int(m1.group(2))
ab = a * b
cd = c * b + d * (a - c)
print(ab - cd)

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

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())
q,a=map(int,input().split())
print((h-q)*(w-a))

Solution (Python):
x = [list(map(int, input().split())) for _ in range(2)]
print((x[0][0] - x[1][0]) * (x[0][1] - x[1][1]))

Solution (Python):
a,a2 = map(int,input().split())
b,b2 = map(int,input().split())
print((a*a2)-((b*a2+b2*a)-(b*b2)))

Solution (Python):
import numpy as np
box_size = list(map(int, input().split())) 
fill_num = list(map(int, input().split())) 
 
box = np.array([[1]*box_size[1]]*box_size[0])
for r in range(fill_num[0]):
    box[r,:] = 0
for c in range(fill_num[1]):
    box[:,c] = 0
print(np.sum(box))

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

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


if (H, W) == (h, w):
    print(0)
else:
    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):
a,b,c,d=map(int,open(0).read().split())
print((a-c)*(b-d))

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())

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

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

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

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

Solution (Python):
import math
def I():
  return input()
def II():
  return int(input())
def MII():
  return map(int, input().split())
def LMII():
  return list(map(int, input().split()))
def P(s):
  return print(s)

a,b = MII()
h,w=MII()
P((a-h)*(b-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())

H_white = H - h
W_white = W - w

print(H_white * W_white)

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] = 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())

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):


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())
t, u = map(int, input().split())

print((h-t)*(w-u))

Solution (Python):


import sys






















def main():
    mod = 1000000007                
    inf = float('inf')              
    
    sys.setrecursionlimit(10**6)    
    def input(): return sys.stdin.readline().rstrip()
    def ii():    return int(input())
    def mi():    return map(int, input().split())
    def mi_0():  return map(lambda x: int(x)-1, input().split())
    def lmi():   return list(map(int, input().split()))
    def lmi_0(): return list(map(lambda x: int(x)-1, input().split()))
    def li():    return list(input())
    
    
    H, W = mi()
    a, b = mi()
    print((H-a) * (W-b))


if __name__ == "__main__":
    main()

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

if __name__ == '__main__':
    main()

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

total = H * W
black = h * W + w * H - h * w
print(total - black)

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

Solution (Python):
stdin = open(0).read().split('\n')
H, W = map(int,stdin[0].split())
h, w = map(int,stdin[1].split())
print(H*W-H*w-h*W+h*w)

Solution (Python):
from collections import defaultdict, deque, Counter
from heapq import heappush, heappop, heapify
from itertools import permutations, accumulate, combinations, combinations_with_replacement
from math import sqrt, ceil, floor, factorial
from bisect import bisect_left, bisect_right, insort_left, insort_right
from copy import deepcopy
from operator import itemgetter
from functools import reduce
from fractions import gcd
import sys
def input(): return sys.stdin.readline().rstrip()
def I(): return int(input())
def Is(): return map(int, input().split())
def LI(): return list(map(int, input().split()))
def TI(): return tuple(map(int, input().split()))
def IR(n): return [I() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def TIR(n): return [TI() for _ in range(n)]
def S(): return input()
def Ss(): return input().split()
def LS(): return list(input())
def SR(n): return [S() for _ in range(n)]
def SsR(n): return [Ss() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
sys.setrecursionlimit(10**6)
MOD = 10**9+7
INF = float('inf')


H, W = Is()
h, w = Is()
print(H*W-h*W-H*w+h*w)

Solution (Python):

import sys


def solve(H: int, W: int, h: int, w: int):
    print((H - h) * (W - w))


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    H = int(next(tokens))  
    W = int(next(tokens))  
    h = int(next(tokens))  
    w = int(next(tokens))  
    solve(H, W, h, w)


if __name__ == '__main__':
    main()

Solution (Python):






import sys
input = sys.stdin.readline

import math
from collections import deque
from fractions import gcd
from functools import lru_cache






MOD = 10**9+7
INF = float('inf')






def inputI(): return int(input().strip())
def inputS(): return input().strip()
def inputIL(): return list(map(int,input().split()))
def inputSL(): return list(map(str,input().split()))
def inputILs(n): return list(int(input()) for _ in range(n))
def inputSLs(n): return list(input().strip() for _ in range(n))
def inputILL(n): return [list(map(int, input().split())) for _ in range(n)]
def inputSLL(n): return [list(map(str, input().split())) for _ in range(n)]


def inv(n): return pow(n, MOD-2, MOD)


kaijo_memo = []
def kaijo(n):
  if(len(kaijo_memo) > n):
    return kaijo_memo[n]
  if(len(kaijo_memo) == 0):
    kaijo_memo.append(1)
  while(len(kaijo_memo) <= n):
    kaijo_memo.append(kaijo_memo[-1] * len(kaijo_memo) % MOD)
  return kaijo_memo[n]

gyaku_kaijo_memo = []
def gyaku_kaijo(n):
  if(len(gyaku_kaijo_memo) > n):
    return gyaku_kaijo_memo[n]
  if(len(gyaku_kaijo_memo) == 0):
    gyaku_kaijo_memo.append(1)
  while(len(gyaku_kaijo_memo) <= n):
    gyaku_kaijo_memo.append(gyaku_kaijo_memo[-1] * pow(len(gyaku_kaijo_memo),MOD-2,MOD) % MOD)
  return gyaku_kaijo_memo[n]

def nCr(n,r):
  if(n == r):
    return 1
  if(n < r or r < 0):
    return 0
  ret = 1
  ret = ret * kaijo(n) % MOD
  ret = ret * gyaku_kaijo(r) % MOD
  ret = ret * gyaku_kaijo(n-r) % MOD
  return ret


def factorization(n):
    arr = []
    temp = n
    for i in range(2, int(-(-n**0.5//1))+1):
        if temp%i==0:
            cnt=0
            while temp%i==0:
                cnt+=1
                temp //= i
            arr.append([i, cnt])
    if temp!=1:
        arr.append([temp, 1])

    if arr==[]:
        arr.append([n, 1])
    return arr


def lcm(a, b):
    return a * b // gcd (a, b)





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

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

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

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 = 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):
import sys
import math
import bisect

def main():
    H, W = map(int, input().split())
    h, w = map(int, input().split())
    ans = H * W - H * w - h * W + h * w
    print(ans)
    
if __name__ == "__main__":
    main()

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

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

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

x = list(map(int,input().split()))

HW = X[0] * X[1]

h = X[1] * x[0]
w = (X[0] * x[1]) - (x[0] * x[1])

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

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

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

Solution (Python):
def ABC_121_A():
    H,W = map(int, input().split())
    h,w = map(int, input().split())
    print(int((H-h)*(W-w)))

if __name__ == '__main__':

    ABC_121_A()

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())
h-=a
w-=b
print(h*w)

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

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

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

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

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):

import sys


def solve(H: int, W: int, h: int, w: int):
    return (H - h) * (W - w)



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    H = int(next(tokens))  
    W = int(next(tokens))  
    h = int(next(tokens))  
    w = int(next(tokens))  
    print(solve(H, W, h, w))

def test():
    import doctest
    doctest.testmod()

if __name__ == '__main__':
    
    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):
a,b=map(int,input().split())
c,d=map(int,input().split())
print(a*b-c*b-a*d+c*d)

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

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())

t=[[0]*W for i in [0]*H]

for i in range(h):
    for j in range(W):
        t[i][j]=1

for i in range(w):
    for j in range(H):
        t[j][i]=1

ans=0

for i in range(H):
    for j in range(W):
        if t[i][j]==0:
            ans+=1

print(ans)

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

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

Solution (Python):
import sys
sys.setrecursionlimit(10 ** 5 + 10)
def input(): return sys.stdin.readline().strip()

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

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

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


main()

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-h)*(W-w))

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

area = H * W
white = area - h * W - (H-h) * w
print(white)

Solution (Python):
a=map(int,open(0).read().split());a,b,c,d=a;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):
H, W = map(int, input().split())
h, w = map(int, input().split())

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

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

ans = H*W
ans -= h * W
ans -= (H-h) * 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):


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