fun main() { val (n, p) = readln().split(" ").map { it.toLong() } var ans = ModInt(0) val cc = CombinationCalculator() for (k in 0..n / p) { ans += cc.fac(n) / (cc.fac(k) * cc.fac(n - k * p) * ModInt(p).pow(k)) } println(cc.fac(n) - ans) } // region ModInt class ModInt(x: Long) { companion object { const val MOD = 998244353L } constructor(y: Int) : this(y.toLong()) val x = (x % MOD + MOD) % MOD operator fun plus(other: ModInt): ModInt { return ModInt(x + other.x) } operator fun minus(other: ModInt): ModInt { return ModInt(x - other.x) } operator fun times(other: ModInt): ModInt { return ModInt(x * other.x) } operator fun div(other: ModInt): ModInt { return this * other.inv() } fun pow(exp: Long): ModInt { if (exp == 0L) return ModInt(1L) var a = pow(exp shr 1) a *= a if (exp and 1L == 0L) return a return this * a } fun inv(): ModInt { return this.pow(MOD - 2) } override fun equals(other: Any?): Boolean { if (this === other) return true if (javaClass != other?.javaClass) return false other as ModInt if (x != other.x) return false return true } override fun hashCode(): Int { return x.hashCode() } override fun toString(): String { return "$x" } } // endregion class CombinationCalculator { companion object { private const val fac_size = 600000 } private val arrFac = Array(fac_size) { ModInt(1) } private val arrInvfac = Array(fac_size) { ModInt(1) } init { for (i in 1 until fac_size) { arrFac[i] = arrFac[i - 1] * ModInt(i) } arrInvfac[fac_size - 1] = arrFac[fac_size - 1].inv() for (i in fac_size - 2 downTo 1) { arrInvfac[i] = arrInvfac[i + 1] * ModInt(i + 1) } } fun fac(n: Int): ModInt { return arrFac[n] } fun fac(n: Long): ModInt { return fac(n.toInt()) } fun invfac(n: Int): ModInt { return arrInvfac[n] } fun invfac(n: Long): ModInt { return invfac(n.toInt()) } fun binom(n: Long, k: Long): ModInt { return if (k in 0..n) { arrFac[n.toInt()] * arrInvfac[k.toInt()] * arrInvfac[(n - k).toInt()] } else { ModInt(0) } } }