import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.lang.AssertionError
import java.util.*
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

val MOD = 998244353

fun powMod(a: Long, n: Long, mod: Int): Long {
  if (n == 0L) return 1
  val res = powMod(a * a % mod, n / 2, mod)
  return if (n % 2 == 1L) res * a % mod else res
}

class Solver(stream: InputStream, private val out: java.io.PrintWriter) {
  private val reader = BufferedReader(InputStreamReader(stream), 32768)

  fun solve() {
    val MOD2 = MOD-1
    val N = nl()
    val M = ni()
    var ans = 0L

    fun arith(n: Int) = n.toLong()*(n + 1)%MOD *((MOD+1)/2) %MOD

    val nsub1 = (MOD2 + N - 1) %MOD2

    val calc = LongArray(M + 1)
    for (i in 1 .. M) {
      calc[i] = powMod(i.toLong(), nsub1, MOD)
    }

    // 最大がiになる組み合わせ
    fun combWithMax(i: Int, n: Long) = (calc[i] + (MOD - calc[i-1])) %MOD

    for (i in 1 .. M) {
      // i as max
      run {
        val combMaxEqI = combWithMax(i, nsub1) // 最大値がi
        val combLeI = calc[i]// i以下
        val c = (arith(i - 1) *combMaxEqI + i*combLeI) %MOD // 貢献度*組み合わせ
//        debug{"$i $c"}
        ans += c *i %MOD // *最大値
      }

      // i as min
      run {
        val combMinEqI = combWithMax(M - (i-1), nsub1) // 最小値がi
        val combGeI = calc[M - (i-1)] // i以上
        val c = ((arith(M) + (MOD - arith(i)))%MOD *combMinEqI + i*combGeI) %MOD
//        debug{"$i $combMinEqI $combGeI $c"}
        ans += (MOD - c) %MOD *i %MOD // *最小値
      }

      ans %= MOD
    }

    out.println(ans *(N%MOD) %MOD)
  }













































  private val isDebug = try {
    // なんか本番でエラーでる
    System.getenv("MY_DEBUG") != null
  } catch (t: Throwable) {
    false
  }

  private var tokenizer: StringTokenizer? = null
  private fun next(): String {
    while (tokenizer == null || !tokenizer!!.hasMoreTokens()) {
      tokenizer = StringTokenizer(reader.readLine())
    }
    return tokenizer!!.nextToken()
  }

  private fun ni() = next().toInt()
  private fun nl() = next().toLong()
  private fun ns() = next()
  private fun na(n: Int, offset: Int = 0): IntArray {
    return IntArray(n) { ni() + offset }
  }
  private fun nal(n: Int, offset: Int = 0): LongArray {
    val res = LongArray(n)
    for (i in 0 until n) {
      res[i] = nl() + offset
    }
    return res
  }

  private fun na2(n: Int, offset: Int = 0): Array<IntArray> {
    val a  = Array(2){IntArray(n)}
    for (i in 0 until n) {
      for (e in a) {
        e[i] = ni() + offset
      }
    }
    return a
  }

  private inline fun debug(msg: () -> String) {
    if (isDebug) System.err.println(msg())
  }

  /**
   * コーナーケースでエラー出たりするので、debug(dp[1])のように添え字付きの場合はdebug{}をつかうこと
   */
  private inline fun debug(a: LongArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: IntArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: BooleanArray) {
    debug { toString(a) }
  }

  private inline fun toString(a: BooleanArray) = run{a.map { if (it) 1 else 0 }.joinToString("")}

  private inline fun debugDim(A: Array<LongArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<IntArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<BooleanArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }

  /**
   * 勝手にimport消されるのを防ぎたい
   */
  private fun hoge() {
    min(1, 2)
    max(1, 2)
    abs(-10)
  }

  private inline fun assert(b: Boolean) = run{if (!b) throw AssertionError()}
  private inline fun assert(b: Boolean, f: () -> String) = run{if (!b) throw AssertionError(f())}
}

fun main() {
  val out = java.io.PrintWriter(System.out)
  Solver(System.`in`, out).solve()
  out.flush()
}