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):


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

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

    print(calc)

if __name__ == "__main__":
    main()

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

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

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

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

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

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

Solution (Python):
A = input().split()
B = input().split()
Cell = int(A[0])*int(A[1])
uni = int(A[0])*int(B[1]) + int(A[1])*int(B[0])
add = int(B[0])*int(B[1])
ans = Cell - uni + add
print(ans)

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):
HW=input().split()
hw=input().split()
print((int(HW[0])-int(hw[0]))*(int(HW[1])-int(hw[1])))

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

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

Solution (Python):


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

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

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







h -= 1
w -= 1

panel = [[1] * W for i in range(H)]

cnt = H * W
for x in range(0, H):
    for y in range(0, W):
        if x <= h or y <= w:
            if 0 < panel[x][y]:
                panel[x][y] = 0
                cnt -= 1


print(cnt)

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):

import sys
try:
    from math import gcd
except Exception:
    from fractions import gcd


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))  
    result = solve(H, W, h, w)
    print(result)

if __name__ == '__main__':
    main()

Solution (Python):
H,W=(int(i) for i in input().split())
h,w=(int(i) for i in 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())
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):
from sys import stdin

H,W = [int(x) for x in stdin.readline().rstrip().split()]
h,w = [int(x) for x in stdin.readline().rstrip().split()]

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

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

Solution (Python):
H,W=map(int,input().split())
h_b,w_b=map(int,input().split())
print((H-h_b)*(W-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):
def sei(a):
  v=[]
  for i in a.split():
    v+=[int(i)]
  return v
a=sei(input())
b=sei(input())
ans=a[0]*a[1]-b[0]*a[1]-(b[1]*a[0]-b[0]*b[1])
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] = 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())

white_cells_int = H * W - ((h * W) + (w * H) - (h * w))
print(str(white_cells_int))

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

Solution (Python):
fh, fw = map(int, input().split())
ch, cw = map(int, input().split())

white = fh*fw - ch*fw - cw*(fh-ch)

print(white)

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

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

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

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

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):
h0, w0 = map(int,input().split(' '))
h1, w1 = map(int, input().split(' '))
print((h0-h1)*(w0-w1))

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

val = H * (W - w)
dis = h*(W-w)
val = val - dis
print(val)

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):
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()))
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 - H * w + h * 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):
import functools

import os

INF = float('inf')


def inp():
    return int(input())


def inpf():
    return float(input())


def inps():
    return input()


def inl():
    return list(map(int, input().split()))


def inlf():
    return list(map(float, input().split()))


def inls():
    return input().split()


def debug(fn):
    if not os.getenv('LOCAL'):
        return fn

    @functools.wraps(fn)
    def wrapper(*args, **kwargs):
        print('DEBUG: {}({}) -> '.format(
            fn.__name__,
            ', '.join(
                list(map(str, args)) +
                ['{}={}'.format(k, str(v)) for k, v in kwargs.items()]
            )
        ), end='')
        ret = fn(*args, **kwargs)
        print(ret)
        return ret

    return wrapper


h, w = inl()
h2, w2 = inl()

print(h * w - h2*w - w2*h + h2*w2)

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-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())

H = max(0, H-h)
W = max(0, 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):
H, W = map(int, input().split())
h, w = map(int, input().split())
print(H * W - (h * W + w * H - h * w))

Solution (Python):

from sys import stdin
H,W = map(int,stdin.readline().rstrip().split())
h,w = map(int,stdin.readline().rstrip().split())
print(H*W-(h*W+H*w-h*w))

Solution (Python):
in1 = input().split()
in2 = input().split()

H = int(in1[0])
W = int(in1[1])

h = int(in2[0])
w = int(in2[1])

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-h)*(W-w))

Solution (Python):
HW=input()
hw=input()
HWlist=HW.split()
hwlist=hw.split()
H=int(HWlist[0])
W=int(HWlist[1])
h=int(hwlist[0])
w=int(hwlist[1])
print(H*W-h*W-H*w+h*w)

Solution (Python):
input1 = input().split()
input2 = input().split()

H = int(input1[0])
W = int(input1[1])
h = int(input2[0])
w = int(input2[1])

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

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

alln = H*W
blan = h*W + w*H - h*w

print(alln-blan)

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())
ans = (h - x) * (w - y)

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

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

Solution (Python):
H, W = [int(c) for c in input().split()]

h, w = [int(c) for c 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):
a, b = input().split()
a, b = int(a), int(b)
row, col = input().split()
row, col = int(row), int(col)
print((a-row)*(b-col))

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 =[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().rstrip().split())
h,w = map(int, input().rstrip().split())
area = H*W
print(area-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):
z = list(map(int,input().split()))
s = list(map(int,input().split()))

print( z[0]*z[1] - ((s[0]*z[1] + s[1]*z[0]) - (s[0]*s[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-h)*(W-w))

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

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

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

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

Solution (Python):
def main():
    arr1 = input()
    arr1 = list(map(int, arr1.split()))
    arr2 = input()
    arr2 = list(map(int, arr2.split()))
    H = int(arr1[0])
    W = int(arr1[1])
    h = int(arr2[0])
    w = int(arr2[1])
    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 = list(map(int, input().split()))

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

print((A - a) * (B - b))

Solution (Python):

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

x=a[0]*a[1]
y=b[0]*b[1]

res=x - ((a[0]*b[1])+(a[1]*b[0])) + y
print(res)

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

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

Solution (Python):



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

print '{}'.format(H*W - (h*W + H*w - 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())

c=h*W+(w*(H-h));

print(H*W-c)

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

ans = white - black
print(ans)

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

Solution (Python):



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

shiro = H * W

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

nokori = shiro - kuro

print(nokori)

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())

n = H*W - h*W - H*w + h*w

print(n)

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

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

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

Solution (Python):
listA = [] 
while True:
    try:
        listA.append(list(map(int,input().split())))

    except:
        break;

H = listA[0][0]
W = listA[0][1]
h = listA[1][0]
w = listA[1][1]

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-w_*(h-h_))

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

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

Solution (Python):
X,Y = map(int,input().split())
A,B = map(int,input().split())
print(X * Y - Y * A - ((X - A) * B))

Solution (Python):
import sys
import math
import collections
import itertools
import array
import inspect


sys.setrecursionlimit(1000000)



def chkprint(*args):
    names = {
        id(v): k
        for k, v in inspect.currentframe().f_back.f_locals.items()
    }
    print(', '.join(
        names.get(id(arg), '???') + ' = ' + repr(arg) for arg in args))



def to_bin(x):
    return bin(x)[2:]


def li_input():
    return [int(_) for _ in sys.stdin.readline().split()]


def gcd(n, m):
    if n % m == 0:
        return m
    else:
        return gcd(m, n % m)


def gcd_list(L):
    v = L[0]

    for i in range(1, len(L)):
        v = gcd(v, L[i])

    return v


def lcm(n, m):
    return (n * m) // gcd(n, m)


def lcm_list(L):
    v = L[0]

    for i in range(1, len(L)):
        v = lcm(v, L[i])

    return v



def wfs_d(D, N, K):
    """
    D: 隣接行列(距離付き)
    N: ノード数
    K: 始点ノード
    """

    dfk = [-1] * (N + 1)
    dfk[K] = 0

    cps = [(K, 0)]
    r = [False] * (N + 1)
    r[K] = True
    while len(cps) != 0:
        n_cps = []
        for cp, cd in cps:
            for i, dfcp in enumerate(D[cp]):
                if dfcp != -1 and not r[i]:
                    dfk[i] = cd + dfcp
                    n_cps.append((i, cd + dfcp))
                    r[i] = True

        cps = n_cps[:]

    return dfk



def dfs_d(v, pre, dist):
    """
    v:  現在のノード
    pre: １つ前のノード
    dist: 現在の距離

    以下は別途用意する
    D: 隣接リスト(行列ではない)
    D_dfs_d: dfs_d関数で用いる，始点ノードから見た距離リスト
    """

    global D
    global D_dfs_d

    D_dfs_d[v] = dist

    for next_v, d in D[v]:
        if next_v != pre:
            dfs_d(next_v, v, dist + d)

    return


def sigma(N):
    ans = 0
    for i in range(1, N + 1):
        ans += i
    return ans


def comb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2, r + 1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p - 1, r, p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

def bisearch(L, target):
    low = 0
    high = len(L) - 1
    
    while low <= high:
        mid = (low + high) // 2
        guess = L[mid]
        if guess == target:
            return True
        elif guess < target:
            low = mid + 1
        elif guess > target:
            high = mid - 1
    if guess != target:
        return False



dp = None


def main():
    H, W = li_input()
    h, w = li_input()

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

    print(S)


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

Solution (Python):
HHH, WWW = map(int, input().split())
h, w = map(int, input().split())

full_cells = HHH * WWW

full_cells -= h * WWW

full_cells -= ((w * HHH) - (h * w))

print(full_cells)

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

Orig = np.ones((H, W))
Orig[0:h, :] =0
Orig[:, 0:w ] =0

total = int(np.sum(Orig))
print(total)

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

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

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

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

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

Solution (Python):
L = input().split()
l = input().split()
print( (int(L[0])-int(l[0])) * (int(L[1])-int(l[1])) )

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

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

output = (HW[0] - hw[0]) * (HW[1] - hw[1])

print(output)

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

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

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

print(output)

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())

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

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

Solution (Python):
H, W = tuple([int(x) for x in input().split(' ')])
h, w = tuple([int(x) for x in 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())
result=(a*b)-(c*b+(a-c)*d)
print(result)

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):
row, col = map(int, input().split(' '))
p_row, p_col = map(int, input().split(' '))
print((row - p_row) * (col - p_col))

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

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

Solution (Python):

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

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

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


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

Solution (Python):
HW = raw_input().split()
hw = raw_input().split()

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

Solution (Python):
HW=input().split()
hw=input().split()
H=int(HW[0])
W=int(HW[1])
h=int(hw[0])
w=int(hw[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+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())

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

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

Solution (Python):
input_1 = input().split()

h_l = int(input_1[0])
w_l = int(input_1[1])

input_2 = input().split()

h = int(input_2[0])
w = int(input_2[1])

result = h_l * w_l - (h_l * w  + w_l * h) + w * h

print(result)

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):
x,y = map(int,input().split())
a,b = map(int,input().split())

gou = x -a 
retu = y - b
print(gou*retu)

Solution (Python):
H,W=input().split()
A=int(H)
B=int(W)

h,w=input().split()
a=int(h)
b=int(w)

print(A*B-A*b-a*B+a*b)

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

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

Solution (Python):

import sys


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



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

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

Solution (Python):


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


if __name__ == "__main__":
    main()

Solution (Python):
X,Y=map(int,input().split())
x,y=map(int,input().split())
a=(X-x)*(Y-y)
print(a)

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())
HM = H * W
hW = W * h
h1 = H - h
h2 = h1 * w
h3 = HM - hW - h2
print(h3)

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):
y, x = list(map(int, input().split()))
_y, _x = list(map(int, input().split()))

yy = x * _y
xx = (y-_y) * _x
z = yy + xx
print((y*x) - z)

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-h)*(W-w))