import kotlin.math.min

fun main() {
    val mod = 998244353
    val (n, m, a, b) = readLine()!!.trim().split(' ').map(String::toInt)
    val factorial = LongArray(m + n + 1){1L}
    val div = LongArray(m + n + 1){1L}
    val inverse = LongArray(m + n + 1){1L}
    for (i in 2 until factorial.size) {
        factorial[i] = i * factorial[i - 1] % mod
        div[i] = (mod - mod / i) * div[mod % i] % mod
        inverse[i] = div[i] * inverse[i - 1] % mod
    }
    val combination = {n: Int, r: Int ->
        if (n >= r) factorial[n] * inverse[r] % mod * inverse[n - r] % mod
        else 0
    }
    val result = (1 .. m).map {smaller ->
        val greater = min(smaller + b, m)
        val diff = greater - a * n.toLong() + a - smaller
        if (diff >= 0)
            combination(diff.toInt() + n - 1, n - 1)
        else
            0
    }
    println(result.sum() % mod * factorial[n] % mod)
}