N, M, A, B = map(int, input().split())
MOD = 998244353
MAX = 3 * 10 ** 5 + 10
# https://tjkendev.github.io/procon-library/python/math/factorial.html から拝借しています。
fact = [1] * (MAX + 1)
rfact = [1] * (MAX + 1)
r = 1
for i in range(1, MAX + 1):
    fact[i] = r = r * i % MOD
rfact[MAX] = r = pow(fact[MAX], MOD - 2, MOD)
for i in range(MAX, 0, -1):
    rfact[i - 1] = r = r * i % MOD


def comb(n, k, error=0):
    if not 0 <= k <= n:
        return error
    return fact[n] * rfact[k] * rfact[n - k] % MOD


ans = 0
for s1 in range(1, M + 1):
    sn = min(s1 + B, M)
    d = sn - s1 - A * (N - 1)
    if d < 0:
        continue
    ans += comb(d + N - 1, N - 1)
    ans %= MOD
ans *= fact[N]
ans %= MOD
print(ans)