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

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

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

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

print(ans)

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

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

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

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

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

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

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

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

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

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

Solution (Python):
H,W = map(int,input().split(" "))
A,B = map(int,input().split(" "))
print((H-A)*(W-B))

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

Solution (Python):
a = list(map(int,input().split()))
H = a[0]
W = a[1]
b = list(map(int,input().split()))
h = b[0]
w = b[1]
print(str((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*W - h*W - H*w + h*w)

Solution (Python):

import copy
import numpy as np
import random

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


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

print(ans)

Solution (Python):
H, W = [int(v) for v in input().split()]
h, w = [int(v) for v in 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())
h1,w1 = map(int,input().split())

print((h-h1)*(w-w1))

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

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

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

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

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

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

print(ans)

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

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

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

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

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

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

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

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

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


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

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

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

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

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

Solution (Python):

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

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

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

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

Solution (Python):
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-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):

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

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

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

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):
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(str((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+H*w-h*w)

print(ans)

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

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

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

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

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

Solution (Python):
import sys
sys.setrecursionlimit(100000)
input=lambda : sys.stdin.readline().rstrip('\n')

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

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

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

Solution (Python):




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

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

  print(x, flush=True)


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):
A,B = map(int,input().split())
a,b = map(int,input().split())

a = A-a
b = B-b

print(a*b)

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

print(H*W - hh*W - ww*H + hh*ww)

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

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

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

Solution (Python):
H,W = 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(int((H-h)*(W-w)))

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

Solution (Python):
from collections import defaultdict


def main():
    H, W = [int(q) for q in input().split()]
    h, w = [int(q) for q in input().split()]

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



if __name__ == '__main__':
    main()

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

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

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

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

Solution (Python):

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

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

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

Solution (Python):
a,b = list(map(int, input().split()))
n,m = list(map(int, input().split()))
print(a*b-n*b-m*a+n*m)

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):
p = input().split()
q = input().split()
print(int(p[0])*int(p[1])-int(q[0])*int(p[1])-int(q[1])*int(p[0])+int(q[1])*int(q[0]))

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

print((hh - h) * (ww - w))

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

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

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

Solution (Python):
if __name__ == '__main__':
    import sys
    input = sys.stdin.readline
    hh,ww = map(int, input().split())
    h, w = map(int, input().split())
    print(hh*ww-h*ww-hh*w+h*w)

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

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

Solution (Python):
h1,w1 = map(int,raw_input().split(" "))
h2,w2 = map(int,raw_input().split(" "))
print (h1-h2)*(w1-w2)

Solution (Python):


import sys, re
from collections import deque, defaultdict, Counter
from math import sqrt, hypot, factorial, pi, sin, cos, radians, log10
if sys.version_info.minor >= 5: from math import gcd
else: from fractions import gcd 
from heapq import heappop, heappush, heapify, heappushpop
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations, product, accumulate
from operator import itemgetter, mul, xor
from copy import copy, deepcopy
from functools import reduce, partial
from fractions import Fraction
from string import ascii_lowercase, ascii_uppercase, digits
from datetime import date

def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def round(x): return int((x*2+1) // 2)
def fermat(x, y, MOD): return x * pow(y, MOD-2, MOD) % MOD
def lcm(x, y): return (x * y) // gcd(x, y)
def lcm_list(nums): return reduce(lcm, nums, 1)
def gcd_list(nums): return reduce(gcd, nums, nums[0])
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
sys.setrecursionlimit(10 ** 9)
INF = float('inf')
MOD = 10 ** 9 + 7

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

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):

"""
Created on Sat Mar  9 20:50:08 2019

@author: Yamazaki Kenichi
"""

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())
h2, w2 = map(int, input().split())
print((h-h2)*(w-w2))

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

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

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

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

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

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

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

Solution (Python):


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

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

Solution (Python):




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


ans = (h1 - h2) * (w1 - w2)


print(ans)

Solution (Python):

"""
This file is part of https://github.com/cheran-senthil/PyRival
Copyright 2019 Cheran Senthilkumar <hello@cheran.io>

"""
from __future__ import division, print_function

import itertools
import os
import sys
from atexit import register
from io import BytesIO


class dict(dict):
    """ dict() -> new empty dictionary """

    def items(self):
        """ D.items() -> a set-like object providing a view on D's items """
        return dict.iteritems(self)

    def keys(self):
        """ D.keys() -> a set-like object providing a view on D's keys """
        return dict.iterkeys(self)

    def values(self):
        """ D.values() -> an object providing a view on D's values """
        return dict.itervalues(self)


def gcd(x, y):
    """ greatest common divisor of x and y """
    while y:
        x, y = y, x % y
    return x


range = xrange

filter = itertools.ifilter
map = itertools.imap
zip = itertools.izip

sys.stdin = BytesIO(os.read(0, os.fstat(0).st_size))
sys.stdout = BytesIO()
register(lambda: os.write(1, sys.stdout.getvalue()))

input = lambda: sys.stdin.readline().rstrip('\r\n')


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

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


if __name__ == '__main__':
    main()

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

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


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

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

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

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

Solution (Python):

import itertools
import collections
import bisect

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):
n1, m1 = map(int, input().split())
n2, m2 = map(int, input().split())
print((n1-n2)*(m1-m2))

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

Solution (Python):
'''
Created on 2019年3月3日

@author: zcg01
'''
import math
import copy
 
 
 
 
def nCast(number):
    if type(number)==str:
        return int(number)
    for idx in range(0,len(number)):
        if type(number[idx])==str:
 
            number[idx]=int(number[idx])
        else:
            nCast(number[idx])
    return number
    
def inputArr(w):
    l=list()
    for idx in range(0,w):
        l.append(input())
    return l
def inputArr1(w):
    l=list()
    for idx in range(0,w):
        l.append(input())
    return l
 
a=nCast(input().split());
b=nCast(input().split());
 

 
def func():

    return (a[0]-b[0])*(a[1]-b[1])
print(func())

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

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

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

val = (hh-h) * (ww-w)
print(val)

Solution (Python):
def main() -> None:
    H, W = map(int, input().split())
    h, w = map(int, input().split())
    print((H - h) * (W - w))


if __name__ == '__main__':
    main()

Solution (Python):

def main():
    h,w = list(map(int,input().split()))
    h2,w2 = list(map(int,input().split()))
    print((h-h2)*(w-w2))

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
input = sys.stdin.readline
h,w = input().split()
h2,w2 = input().split()
h = int(h)
w = int(w)
h2 = int(h2)
w2 = int(w2)
print((h - h2) * (w - 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):
H,W=map(int,input().split())
h,w=map(int,input().split())
print((H-h)*(W-w))

Solution (Python):


import math
import numpy as np
import random
import copy
import statistics 
import bisect
import heapq
from collections import defaultdict 

N,W = [int(x) for x in input().split()]
h,w = [int(x) for x in input().split()]

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

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

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

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

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
stdin = sys.stdin
 
sys.setrecursionlimit(10**5) 
 
def li(): return map(int, stdin.readline().split())
def li_(): return map(lambda x: int(x)-1, stdin.readline().split())
def lf(): return map(float, stdin.readline().split())
def ls(): return stdin.readline().split()
def ns(): return stdin.readline().rstrip()
def lc(): return list(ns())
def ni(): return int(stdin.readline())
def nf(): return float(stdin.readline())

H,W = li()
h,w = li()
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):
b=list(map(int,input().split()))
c=list(map(int,input().split()))
print((b[0]-c[0])*(b[1]-c[1]))

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

Solution (Python):
h0, w0 = [int(_) for _ in input().split(' ')]
h, w = [int(_) for _ in input().split(' ')]
print((h0 - h) * (w0 - w))

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

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

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

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

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

Solution (Python):
H, W = (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-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*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):
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque, OrderedDict
from copy import deepcopy
from functools import lru_cache, reduce
from math import ceil, floor
from sys import setrecursionlimit

import heapq
import itertools
import operator


inf = float('inf')


def get_int():
    return int(input())


def get_float():
    return float(input())


def get_str():
    return input().strip()


def get_list_of_int():
    return [int(i) for i in input().split()]


def get_list_of_float():
    return [float(f) for f in input().split()]


def get_list_of_char():
    return list(input().strip())


def get_data(n, order=None, **kwargs):
    if not order:
        order = range(len(kwargs))
    it = iter(order)
    var, fn = zip(*sorted(sorted(kwargs.items()), key=lambda _: next(it)))

    rows = []
    for _ in range(n):
        rows.append(input().split())
    columns = zip(*rows)
    exec("global "+", ".join(var)+"\n"+"\n".join(
        v+"=list(map(fn[{}], data[{}]))".format(i, i)
        for i, v in enumerate(var)),
        globals(),
        {"fn": list(fn), "data": list(columns)}
    )
    return



H, W = 0, 0
h, w = 0, 0


def set_inputs():
    global H, W, h, w
    H, W = get_list_of_int()
    h, w = get_list_of_int()
    return


def main():
    setrecursionlimit(100000)
    set_inputs()
    print((H - h) * (W - w))
    return


if __name__ == '__main__':
    main()

Solution (Python):



from itertools import chain
from functools import reduce
from collections import OrderedDict, Counter, deque
import operator

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

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

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

Solution (Python):

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

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

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

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

print(h*w - (hh*w + ww*h - hh*ww))

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

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

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

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

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

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

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

Solution (Python):
h,w = map(int,input().split())
h_,w_ = map(int,input().split())

print(h*w - h*w_ - h_*w +h_*w_)

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

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

Solution (Python):

n, m = map(int,input().split())
s, t = map(int,input().split())

k = (n-s)*(m-t)

print(k)

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

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

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

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

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

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

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

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

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

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

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

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*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())
r, c = map(int, input().split())

print((H - r) * (W - c))

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,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):

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

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

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

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-H*w+h*w)

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

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

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

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

Solution (Python):
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())

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

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

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()))

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

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())
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))