import sys
input = sys.stdin.readline

MAX = 10**6
MOD = 998244353
fact = [0]*MAX #fact[i]: i!
inv = [0]*MAX #inv[i]: iの逆元
finv = [0]*MAX #finv[i]: i!の逆元
fact[0] = 1
fact[1] = 1
finv[0] = 1
finv[1] = 1
inv[1] = 1
    
for i in range(2, MAX):
    fact[i] = fact[i-1]*i%MOD
    inv[i] = MOD-inv[MOD%i]*(MOD//i)%MOD
    finv[i] = finv[i-1]*inv[i]%MOD

def C(n, r):
    if n<r:
        return 0
    if n<0 or r<0:
        return 0
    return fact[n]*(finv[r]*finv[n-r]%MOD)%MOD

N, M, A, B = map(int, input().split())
ans = 0

for m in range(M):
    if m>B:
        break
    
    ans += (M-m)*C(m-(N-1)*A+N-2, N-2)
    ans %= MOD
    
ans *= fact[N]
ans %= MOD
print(ans)