n,m,a,b = map(int,input().split())
mod = 998244353

## nCkのmodを求める関数
# テーブルを作る(前処理)
max_n = 3 * 10**5 + 100
fac, finv, inv = [0]*max_n, [0]*max_n, [0]*max_n

def comInit(max_n):
    fac[0] = fac[1] = 1
    finv[0] = finv[1] = 1
    inv[1] = 1

    for i in range(2,max_n):
      fac[i] = fac[i-1]* i% mod
      inv[i] = mod - inv[mod%i] * (mod // i) % mod
      finv[i] = finv[i-1] * inv[i] % mod

comInit(max_n)

# 二項係数の計算
def com(n,k):
    if(n < k):
        return 0
    if( (n<0) | (k < 0)):
        return 0
    return fac[n] * (finv[k] * finv[n-k] % mod) % mod

ans = 0
for left in range(1,m+1):
    balls = m - left - a*(n-1)
    if(balls < 0):
        break
    balls = min(balls , b-a*(n-1))
    ans += com( balls + 1 + n-2, balls )
    ans %= mod

ans *= fac[n]
ans %= mod
print(ans)