import io
import sys
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, accumulate
from heapq import heappush, heappop
from bisect import bisect_right, bisect_left
from math import gcd
import math

_INPUT = """\
6
2 3 1 2
1 1 1 1
13223 2930 50 222
"""

mod=998244353
def solve(test):
  H,W,A,B=map(int,input().split())
  h,w=H-A+1,W-B+1
  a,b=min(H-A+1,A),min(W-B+1,B)
  if H//2>=a:  m =2*a*(a+1)*(2*a+1)//6+a**2*(H-2*a)
  elif H%2==0: m =2*(H//2)*(H//2+1)*(H+1)//6
  else:        m =2*(H//2)*(H//2+1)*(H+1)//6+(H//2+1)**2
  if W//2>=b:  m*=2*b*(b+1)*(2*b+1)//6+b**2*(W-2*b)
  elif W%2==0: m*=2*(W//2)*(W//2+1)*(W+1)//6
  else:        m*=2*(W//2)*(W//2+1)*(W+1)//6+(W//2+1)**2
  print((2*A*B*h**2*w**2-m)*pow(h*w,2*(mod-2),mod)%mod)

def random_input():
  from random import randint,shuffle
  N=randint(1,10)
  M=randint(1,N)
  A=list(range(1,M+1))+[randint(1,M) for _ in range(N-M)]
  shuffle(A)
  return (" ".join(map(str, [N,M]))+"\n"+" ".join(map(str, A))+"\n")*3

def simple_solve():
  return []

def main(test):
  if test==0:
    solve(0)
  elif test==1:
    sys.stdin = io.StringIO(_INPUT)
    case_no=int(input())
    for _ in range(case_no):
      solve(0)
  else:
    for i in range(1000):
      sys.stdin = io.StringIO(random_input())
      x=solve(1)
      y=simple_solve()
      if x!=y:
        print(i,x,y)
        print(*[line for line in sys.stdin],sep='')
        break

#0:提出用、1:与えられたテスト用、2:ストレステスト用
main(0)