#include <bits/stdc++.h>
using ll = long long;
using matrix = std::array<std::array<int, 3>, 3>;

const int mod = 998244353;

matrix operator*(matrix a, matrix b) {
  matrix c{};
  for (int i : {0, 1, 2})
    for (int k : {0, 1, 2})
      for (int j : {0, 1, 2}) (c[i][j] += (ll)a[i][k] * b[k][j] % mod) %= mod;
  return c;
}

matrix qpow(matrix x, int y) {
  auto ret = (--y, x);
  for (; y; y >>= 1, x = x * x)
    if (y & 1) ret = ret * x;
  return ret;
}

int f(int n, int m) {
  static std::map<std::pair<int, int>, int> mp;
  if (mp.count({n, m})) return mp[{n, m}];
  if (m == 0) return 1;
  if (m == 1) {
    matrix a{};
    a[0][1] = 1;
    a[1][0] = 1;
    a[1][2] = 1;
    a[2][0] = 1;
    int ret = 0;
    auto b = qpow(a, n - 1);
    (ret += (b[0][1] + b[0][2]) % mod) %= mod;
    b = qpow(a, n - 2);
    (ret += ((b[0][1] + b[0][0]) % mod + b[2][0]) % mod) %= mod;
    return mp[{n, m}] = ret;
  }
  if (m & 1)
    return mp[{n, m}] = (ll)f(n, (m - 1) / 2) * f(n, 1) % mod;
  else
    return mp[{n, m}] = (f(n, m / 2) + f(n, m / 2 - 1)) % mod;
}

int main() {
  std::cin.tie(0)->sync_with_stdio(0);
  int n, m;
  std::cin >> n >> m;
  std::cout << f(n, m) << '\n';
}