MOD = 998244353i64

n, m = read_line.split.map(&.to_i)
all = (pow(2i64, n) + MOD - 1)
half = (pow(2i64, n - 1) + MOD - 1)
v0 = 1i64
v1 = 1i64
(m - 1).times do |i|
  den = inv(i + 1)
  v0 *= all
  v0 %= MOD
  v0 *= den
  v0 %= MOD
  v1 *= half
  v1 %= MOD
  v1 *= den
  v1 %= MOD
  all -= 1
  half -= 1
end
v0 *= all
v0 %= MOD
v0 *= inv(m)
v0 %= MOD
puts (v0 - v1 * (pow(2i64, n) - 1) % MOD + MOD) % MOD

def inv(v : Int64)
  pow(v, MOD - 2)
end

def pow(v : Int64, p)
  ret = 1i64
  while p > 0
    if (p & 1i64) != 0
      ret *= v
      ret %= MOD
    end
    v *= v
    v %= MOD
    p >>= 1
  end
  ret
end