MOD = 998244353
N, M, A, B = map(int, input().split())
N2 = 10 ** 6
fact = [1] * (N2 + 1)
rfact = [1] * (N2 + 1)
r = 1
for i in range(1, N2 + 1):
    fact[i] = r = r * i % MOD
rfact[N2] = r = pow(fact[N2], -1, MOD)
for i in range(N2, 0, -1):
    rfact[i - 1] = r = r * i % MOD


# nCk (mod MOD) を求める
def comb(n, k):
    return fact[n] * rfact[k] * rfact[n - k] % MOD


minr = A * (N - 1)
f = fact[N]
if minr > B:
    print(0)
    exit()

ans = 0
for i in range(1, M - minr + 1):
    maxl = min(M, i + B)
    a = maxl - i - A * (N - 1)
    ans += comb(a + N - 1, N - 1)
print((ans * f) % MOD)