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())
	m = []
	for i in range(H):
		t = []
		for j in range(W):
			t.append(1)
		m.append(t)
	for i in range(h):
		for j in range(W):
			m[i][j] = 0
	for i in range(w):
		for j in range(H):
			m[j][i] = 0
	s = 0
	for i in range(H):
		s += sum(m[i])
	print(s)
	return

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())

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 + h*W - h*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):
inp =input().split()
inp2=input().split()

s = int(inp[0]) - int(inp2[0])
d = int(inp[1]) - int(inp2[1])

k = s * d
print(k)

Solution (Python):


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

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

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())
sh, sw  = map(int, input().split())

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

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

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

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


'''考え方
(H-h)行*(W-w)列
'''
output = (H-h) * (W-w)

print(output)

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-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=map(int,input().split())
h2,w2=map(int,input().split())
val1=h1*w1
val2=h2*w1+(h1*w2)
val2-=(h2*w2)
print(val1-val2)

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

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

Solution (Python):
""" AtCoder """

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

h2 = H - h
w2 = W - w

print(h2*w2)

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()))
H = HW[0]
W = HW[1]
hw = list(map(int, input().split()))
h =hw[0]
w = hw[1]
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-h)*(W-w))

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

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

print(x)

Solution (Python):
import math, string, itertools, fractions, heapq, collections, re,  array, bisect, sys, random, time, copy, functools


sys.setrecursionlimit(10**7)
inf = 10 ** 20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1, 0), (0, 1), (1, 0), (0, -1)]
ddn = [(-1, 0), (-1, 1), (0, 1), (1, 1), (1, 0), (1, -1), (0, -1), (-1, -1)]


def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


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

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

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

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

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

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

a = h*w
ans1 = H*W 
ans2 = h*W
ans3 = w*H

print(ans1 - ans2 - ans3 + 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())
masu_all = H * W
print(masu_all - w * H - h * (W-w))

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

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

tot = H * W

rows = h * W
cols = H * w
common = h * w

print(tot - rows - cols + common)

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

total = H*W
black = (h*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):
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):

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 = [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())

n = H*W

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

print(n)

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

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

H -= h
W -= w

print(H*W)

Solution (Python):


"""
Created on 2019/3/9
Solved on 2019/3/9
@author: shinjisu
"""






def getInt(): return int(input())


def getIntList(): return [int(x) for x in input().split()]


def zeros(n): return [0]*n


def getIntLines(n): return [int(input()) for i in range(n)]


def getIntMat(n):
    mat = []
    for i in range(n):
        mat.append(getIntList())
    return mat


def zeros2(n, m): return [zeros(m)]*n


ALPHABET = [chr(i+ord('a')) for i in range(26)]
DIGIT = [chr(i+ord('0')) for i in range(10)]
N1097 = 10**9 + 7
INF = 10**12


def dmp(x, cmt=''):
    global debug
    if debug:
        if cmt != '':
            print(cmt, ':  ', end='')
        print(x)
    return x


def prob_A():
    H, W = getIntList()
    h, w = getIntList()
    dmp((H, W))
    dmp((h, w))
    ans = (H-h)*(W-w)
    return ans


debug = False  
ans = prob_A()
print(ans)




def prob_B():
    A, B, K = getIntList()
    dmp((A, B, K))
    count = 0
    i = 100
    while count < K:
        if A % i == 0 and B % i == 0:
            count += 1
            if count == K:
                break
        i -= 1
    return i


def prob_C():
    S = input()
    red = 0
    blue = 0
    for cube in S:
        if cube == '0':
            red += 1
        else:
            blue += 1
    dmp((red, blue))
    return min(red, blue)*2


def prob_D():
    global N, M, A, B
    N, M = getIntList()
    dmp((N, M))
    A = zeros(M)
    B = zeros(M)
    for i in range(M):
        A[i], B[i] = getIntList()
    dmp(A, 'A')
    dmp(B, 'B')
    count = dmp(countInconv(), 'orginal')
    for i in range(M):
        A[i] = -1
        B[i] = -1
        dmp(A, 'A')
        dmp(B, 'B')
        print(countInconv())
    return count

Solution (Python):
x = input()
y = x.split(" ")
map = [int(i) for i in y]
x = input()
y = x.split(" ")
cell = [int(i) for i in y]
map[0] = map[0] - cell[0]
map[1] = map[1] - cell[1]
print(map[0]*map[1])

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 - White Cells
"""


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, raw_input().strip().split())
h, w = map(int, raw_input().strip().split())

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

print w

Solution (Python):


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

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

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

Solution (Python):

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

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

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

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

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

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):
import collections
import itertools
import numpy as np
import sys
def IL(): return list(map(int,input().split()))
def SL(): return input().split()
def I(): return int(sys.stdin.readline())
def S(): return input()

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

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(" "))

sum1 = H * w
sum2 = W * h
sum3 = h * w
sum4 = H * W

print(sum4 - (sum1 + sum2 - sum3))

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 numpy as np


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

Solution (Python):
H,W=[int(i) for i in input().split()]
h,w=[int(i) for i in 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((c-a)*(d-b))

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

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

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

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

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

Solution (Python):
s = [input().split() for i in range(2)]
H = int(s[0][0])
W = int(s[0][1])
h = int(s[1][0])
w = int(s[1][1])

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

all_cell = H * W

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

print(all_cell)

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

Solution (Python):
import itertools


def main():
    h, w = (int(z) for z in input().split())
    n, m = (int(z) for z in input().split())
    res = 0
    for r, c in itertools.product(range(h), range(w)):
        if 0 <= r < n or 0 <= c < m:
            pass
        else:
            res += 1
    print(res)


if __name__ == "__main__":
    main()

Solution (Python):
h,w = map(int, raw_input().split())
mat = [[0 for i in xrange(w)] for j in xrange(h)]
a,b = map(int, raw_input().split())
for i in xrange(a):
	for j in xrange(w):
		mat[i][j] = 1
for i in xrange(b):
	for j in xrange(h):
		mat[j][i] = 1
ans = 0
for i in xrange(h):
	for j in xrange(w):
		ans += mat[i][j]
print h*w-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())
a,b = map(int, input().split())

s = h*w
t = a*w
y = b*h-a*b
print(s-(t+y))

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

Solution (Python):
H,W = input().split()
h,w = input().split()
A = int(H)
B = int(W)
a = int(h)
b = int(w)
C = (A-a)*(B-b)
print(C)

Solution (Python):
Height,Width = list(map(int,input().split()))
h,w = list(map(int,input().split()))

print((Height-h)*(Width-w))

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

Solution (Python):
H,W=[int(z) for z in input().split(" ")]
h,w=[int(z) for z in 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]*a[1] - b[0] * a[1] - b[1]*a[0] + b[0]*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())
res = (H - h) * (W - w)
print(res)

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

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

print(H * W - ans)

Solution (Python):

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

Solution (Python):
from sys import exit

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

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

black = h * w

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

print(white)

Solution (Python):
h,w=map(int,input().split())
h1,w1=map(int,input().split())
b=(h-h1)*(w-w1)
print(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):
temp = input().split(" ")
a = temp[0]
b = temp[1]
temp = input().split(" ")
c = temp[0]
d = temp[1]
x = int(a) - int(c)
y = int(b) - int(d)
print(x*y)

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

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

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

Solution (Python):
H, W = map(int, input().split())
h1, w1 = map(int, input().split())

print(H * W - h1 * W - w1 * H + h1 * w1)

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

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

Solution (Python):
h0,w0 = map(int,input().split())
h,w= map(int,input().split())
print((h0-h)*(w0-w))

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

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

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

Solution (Python):
h1,w1=map(int,input().split())
h2,w2=map(int,input().split())

print((h1-h2)*(w1-w2))

Solution (Python):
lh, lw = list(map(int, input().split()))
h, w = list(map(int, input().split()))

ans = lh*lw - h*lw - w*lh +h*w
print(ans)

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

a = H-h
b = W-w

print(str(a*b))

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

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

Solution (Python):
i = list(map(int, input().split()))
H = i[0]
W = i[1]
i1 = list(map(int, input().split()))
h = i1[0]
w = i1[1]

A = H - h
B = W - w

print(A * B)

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

x = (b - d) * (a - c)

if(x <= 0):
    print(0)
else:
    print(x)

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

Solution (Python):
import sys
stdin = sys.stdin
 
sys.setrecursionlimit(10**5) 
 
def li(): return map(int, stdin.readline().split())

H, W = tuple(li())
h, w = tuple(li())

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

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-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-W*h)

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):
HW = list(map(int,input().strip().split()))
hw = list(map(int,input().strip().split()))

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

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

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

Solution (Python):


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

Solution (Python):
def solve(ch, cw, h, w):
    print((ch - h)*(cw - w))

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

solve(ch, cw, h, w)

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

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

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

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

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

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

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

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

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

Solution (Python):
h1, w1 = (int(i) for i in input().split())
h2, w2 = (int(i) for i in 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_max, w_max = map(int, input().split())
h, w = map(int, input().split())

print((h_max - h) * (w_max - 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())
n,k=map(int,input().split())

print((h-n)*(w-k))

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-w*a+w*h)

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

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

'''
N=int(input())
N,M=list(map(int,input().split()))
S=input()

li=[]
for i in range(N):
    li.append(list(map(int,input().split())))
'''

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

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

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

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

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):
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):

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

def main():
    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)



if __name__ == '__main__':
    main()

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

print(Total - black)

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

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

Solution (Python):


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



if __name__ == '__main__':
    main()

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

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

p = H*W
q = h*W+w*(H-h)

print(p-q)

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

def main():
	H, W = map(int, input().split())
	h, w = map(int, input().split())
	if H == h or W == w:
		print("0")
	else:
		print((H - h) * (W - w))	

if __name__ == '__main__':
	main()

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

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

print(all_num)

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

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

Solution (Python):
lst=input().split(" ")
H=int(lst[0])
W=int(lst[1])
lst=input().split(" ")
h=int(lst[0])
w=int(lst[1])

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

Solution (Python):
from sys import stdin

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

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

input = lambda: stdin.readline()
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):
data = input().split()
H = int(data[0])
W = int(data[1])
data = input().split()
h = int(data[0])
w = int(data[1])

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

print(sou)

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

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

Solution (Python):
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+w*h)

Solution (Python):
a,b = map(int, input().split())
h,w = map(int, input().split())
white=a*b-h*b-a*w+h*w
print(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*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 + 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 = [int(_) for _ in input().split()]
h, w = [int(_) for _ 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())
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):
[h1,w1] = [int(i) for i in input().split()]
[h2,w2] = [int(i) for i in input().split()]
print(h1*w1 - h2*w1 - w2*h1 + h2 * w2)

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

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

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

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

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

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

Solution (Python):
x,y=list(map(int,input().split(" ")))
m,n=list(map(int,input().split(" ")))
print((x-m)*(y-n))

Solution (Python):
h,w=map(int,input().split())
h1,w1=map(int,input().split())
print(h*w-(h1*w+w1*h-h1*w1))

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

Solution (Python):
list1=input().split(' ')
a=int(list1[0])
b=int(list1[1])
list2=input().split(' ')
c=int(list2[0])
d=int(list2[1])
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 - w * h))

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

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):
import sys
def myin():
    for s in sys.stdin:
        for t in s.split():
            yield t

_in=myin()
H,W=int(next(_in)),int(next(_in))
h,w=int(next(_in)),int(next(_in))
print(H*W-(h*W+w*H-w*h))

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

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