fun main() {
    val (a, b) = readLongs()
    fun fac(n: Long) = (1..n).map { ModInt(it) }.fold(ModInt(1), ModInt::times)
    println(fac(a + b - 2) / (fac(a - 1) * fac(b - 1)))
}

// region ModInt
class ModInt(x: Long) {
    companion object {
        const val MOD = 998244353L
    }

    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 toString(): String {
        return "$x"
    }
}
// endregion

fun readLongs() = readln().split(" ").map { it.toLong() }