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())
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())

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

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

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

Solution (Python):
H1, W1 = map(int, input().split())
H2, W2 = map(int, input().split())

H=H1-H2
W=W1-W2

print(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+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())
i,j = map(int,input().split())
print((h-i)*(w-j))

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*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+w*h)

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

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

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

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):

def input2():
	return map(int,input().split())

H,W=input2()
h,w=input2()

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

Solution (Python):
rows, columns = map(int, input().split())
black_rows, black_columns = map(int, input().split())

area = rows * columns
black_space = black_columns * rows + black_rows * columns - black_rows * black_columns

print(area - black_space)

Solution (Python):
def mapt(fn, *args):
    return tuple(map(fn, *args))


def Input():
    return mapt(int, input().split(" "))


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

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-h)*(W-w))

Solution (Python):
H, W = map(int, input().split())
h, w = map(int, input().split())
ans = H * W - H * w - h * W + 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())
white = H*W
black = (W*h) + ((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):
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+w*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=list(map(int,input().split()))
h,w=list(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-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 * 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*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*W-h*W-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):
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 - 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-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 = [int(i) for i in input().split()]
n = (H-h) * (W-w)
print(n)

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

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

HW=[]

for i in range(H):
  sublist=[]
  for j in range(W):
    sublist.append(0)
  HW.append(sublist)



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



for i in range(w):
  for j in range(H):
    if HW[j][i]==1: continue
    HW[j][i]=1

cnt=0

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

print(cnt)

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

Solution (Python):
n,m=map(int,input().split())
x,y=map(int,input().split())
print(n*m-x*m-y*n+x*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())
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):
import sys

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


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

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

    return


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):
import sys
a, b, c, d = map(int, sys.stdin.read().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 ())
x = H-h
y = W-w
print (x*y)

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*w)

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-h)*w)
print(ans)

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

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

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

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

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 = map(int, input().split())
a,b = map(int, input().split())
print((x-a)*(y-b))

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

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

Solution (Python):
import sys
def MI(): return map(int,sys.stdin.readline().rstrip().split())

H,W = MI()
h,w = MI()
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):
import bisect, collections, copy, heapq, itertools, math, string, sys
input = lambda: sys.stdin.readline().rstrip() 
sys.setrecursionlimit(10**7)
INF = float('inf')
def I(): return int(input())
def F(): return float(input())
def SS(): return input()
def LI(): return [int(x) for x in input().split()]
def LI_(): return [int(x)-1 for x in input().split()]
def LF(): return [float(x) for x in input().split()]
def LSS(): return input().split()

def resolve():
    H, W = LI()
    h, w = LI()

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

if __name__ == '__main__':
    resolve()

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-W*h-(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())

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

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):
n,m=map(int,input().split())
a,b=map(int,input().split())
print((n-a)*(m-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 = list(map(int,input().split()))
h,w = list(map(int,input().split()))
print((H-h) * (W - w))

Solution (Python):
import sys


stdin = sys.stdin
def ns(): return stdin.readline().rstrip()
def ni(): return int(stdin.readline().rstrip())
def nm(): return map(int, stdin.readline().split())
def nl(): return list(map(int, stdin.readline().split()))


def main():
    H, W = nm()
    h, w = nm()
    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):
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*W - W*x - (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())

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

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-hh)*(w-ww))

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

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

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

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

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

print(h*w-h*b-w*a+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=map(int,input().split())
h,w=map(int,input().split())
S=H*W
print(S-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):
ary = input().split(" ")
H = int(ary[0])
W = int(ary[1])
aryary = input().split(" ")
h = int(aryary[0])
w = int(aryary[1])

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+1*(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)-(W*h+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
if ans < 0:
  print(0)
else:
  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):



















































def calculation(lines):
    
    
    H, W = list(map(int, lines[0].split()))
    h, w = list(map(int, lines[1].split()))
    
    
    
    

    return [(H-h)*(W-w)]



def get_input_lines(lines_count):
    lines = list()
    for _ in range(lines_count):
        lines.append(input())
    return lines



def get_testdata(pattern):
    if pattern == 1:
        lines_input = ['3 2', '2 1']
        lines_export = [1]
    if pattern == 2:
        lines_input = ['5 5', '2 3']
        lines_export = [6]
    if pattern == 3:
        lines_input = ['2 4', '2 4']
        lines_export = [0]
    return lines_input, lines_export



def get_mode():
    import sys
    args = sys.argv
    if len(args) == 1:
        mode = 0
    else:
        mode = int(args[1])
    return mode



def main():
    import time
    started = time.time()
    mode = get_mode()
    if mode == 0:
        lines_input = get_input_lines(2)
    else:
        lines_input, lines_export = get_testdata(mode)

    lines_result = calculation(lines_input)

    for line_result in lines_result:
        print(line_result)

    
    
    
    
    
    
    
    
    
    
    



if __name__ == '__main__':
    main()

Solution (Python):
import sys

input = sys.stdin.readline


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

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


if __name__ == "__main__":
    main()

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

start_state = H * W
deduct_state = h * W + w * H - h * w

answer = start_state - deduct_state

print(answer)

Solution (Python):
H,W = map(int,input().split())
Record,Column = map(int,input().split())

print((H-Record)*(W-Column))

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-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())

all = H * W

ans = all - (h * W) - (w * H) + w * h
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 = [int(n) for n in input().split()]
h, w = [int(n) for n in 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())

S = H * W

left = S - ((h * W) + (w * H) - (w * h))

print(left)

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

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

Solution (Python):
import sys

H, W = map(int, sys.stdin.readline().split())
h, w = map(int, sys.stdin.readline().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 * 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):
HW =[list(map(int,input().split())) for i in range(2)]
print((HW[0][0]-HW[1][0])*(HW[0][1]-HW[1][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())
a, b = map(int, input().split())
print(H*W-H*b-W*a+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 = map(int, input().split())
r, c = map(int, input().split())
print((h - r) * (w - c))

Solution (Python):
import sys
sys.setrecursionlimit(10**6)

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

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

Solution (Python):






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

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


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

Solution (Python):
import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    h, w = map(int, readline().split())
    p, q = map(int, readline().split())

    print(h * w - p * w - q * (h - p))


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

Solution (Python):
h, w = [int(i) for i in input().split()]
h1, w1 = [int(i) for i in input().split()]
 
print(h * w - (h * w1 + w * h1 - h1 * w1))

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

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())
S=H*W-(H*w+W*h)+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):
import sys
input = lambda: sys.stdin.readline().rstrip()

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

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):
import sys
H,W = map(int,input().split())
h,w = map(int,input().split())
array = [[0]*W for I in range(H)]

for I in range(h):
    array[I] = [1]*W

array = [list(x) for x in zip(*array)]

for I in range(w):
    array[I] = [1]*H

array = [list(x) for x in zip(*array)]

count = 0
for I in range(H):
    count += array[I].count(0)
print(count)

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):

 

 
import sys
from fractions import gcd
import math
from math import ceil,floor
import collections
from collections import Counter
import itertools
import copy
 

 










 
H,W=map(int, input().split())
S,T=map(int, input().split())

print(H*W - W*S - (H-S)*T)

Solution (Python):
import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline

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):
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 = list(map(int, input().split()))
c, d = list(map(int, input().split()))

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

Solution (Python):
h,w = map(int,input().split())
erase_h,erase_w = map(int,input().split())

white_b = h*w

erase = erase_h*w + erase_w*h - (erase_h*erase_w)

print(white_b - erase)

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 - h) * w))

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*w)

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

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

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

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

Solution (Python):
h1,w1,h2,w2=map(int,open(0).read().split());
print((h1-h2)*(w1-w2))

Solution (Python):
import sys
rm = lambda: map(int, sys.stdin.buffer.readline().split())

a, b = rm()
c, d = rm()
print((c-a) * (d-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):
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):
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-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())
h1,w1=map(int,input().split())
print((h*w)-(w*h1)-((h-h1)*w1))

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=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())

allmenseki = H*W

kuro_yoko = h*W

kuro_tate = (H-h)*w

siro = allmenseki - (kuro_yoko + kuro_tate)

print(siro)

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-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())
h,w = 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=list(map(int,input().split()))
C,D=list(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-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
input=sys.stdin.readline
sys.setrecursionlimit(10 ** 8)
from itertools import accumulate
from itertools import permutations
from itertools import combinations
from collections import defaultdict
from collections import Counter
import fractions
import math
from collections import deque
from bisect import bisect_left
from bisect import bisect_right
from bisect import insort_left
import itertools
from heapq import heapify
from heapq import heappop
from heapq import heappush
import heapq
from copy import deepcopy
from decimal import Decimal
alf = list("abcdefghijklmnopqrstuvwxyz")
ALF = list("ABCDEFGHIJKLMNOPQRSTUVWXYZ")

INF = float("inf")


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

Solution (Python):

import sys
input = sys.stdin.readline
H,W = (int(i) for i in input().split())
h,w = (int(i) for i in input().split())
common =h*w
ans = H*W -h*W -H*w +common
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,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+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*W-H*w-W*h+h*w)

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

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

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 - h) * (W - w))