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

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

Solution (Python):
from statistics import mean, median,variance,stdev
import numpy as np
import sys
import math
import fractions
import itertools
import copy

def j(q):
    if q==1: print("YES")
    else:print("NO")
    exit(0)


def ct(x,y):
    if (x>y):print("GREATER")
    elif (x<y): print("LESS")
    else: print("EQUAL")

def ip():
    return int(input())

h,w= (int(i) for i in input().split())       









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

Solution (Python):


from collections import deque
import itertools as it
import sys
import math

sys.setrecursionlimit(1000000)

INF = 10 ** 18

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

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

Solution (Python):

A, B = map(int, input().split())
A2, B2 = map(int, input().split())

print((A-A2)*(B-B2));

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(_) for _ in input().split()]
h, w = [int(_) for _ in input().split()]

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

Solution (Python):
ri = lambda: int(input())
rl = lambda: list(map(int,input().split()))
rr = lambda N: [ri() for _ in range(N)]
YN = lambda b: print('YES') if b else print('NO')
yn = lambda b: print('Yes') if b else print('No')
OE = lambda x: print('Odd') if x%2 else print('Even')
INF = 10**18

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

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

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 sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().rstrip()  

h, w = na()
hh, ww = na()
print((h-hh)*(w-ww))

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

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