#include <bits/stdc++.h>

using namespace std;

const int MOD = 998244353;
class Matrix {
 public:
  int n, m;
  int v[4][4];
  Matrix(int _n = 0, int _m = 0) : n(_n), m(_m) {
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= m; j++) {
        v[i][j] = 0;
      }
    }
  }
  friend Matrix operator*(const Matrix& a, const Matrix& b) {
    assert(a.m == b.n);
    Matrix res(a.n, b.m);
    for (int i = 1; i <= a.n; i++) {
      for (int k = 1; k <= a.m; k++) {
        for (int j = 1; j <= b.m; j++) {
          res.v[i][j] = (res.v[i][j] + 1LL * a.v[i][k] * b.v[k][j]) % MOD;
        }
      }
    }
    return res;
  }
};

Matrix qpow(Matrix a, int b) {
  Matrix res(a.n, a.m);
  assert(a.n == a.m);
  for (int i = 1; i <= a.n; i++) {
    res.v[i][i] = 1;
  }
  while (b) {
    if (b & 1) {
      res = res * a;
    }
    a = a * a;
    b >>= 1;
  }
  return res;
}

int n, m;
int o;

map<int, int> ret;

int solve(int m) {
  if (m == 0) {
    return 1;
  }
  if (m == 1) {
    return o;
  }
  if (ret.find(m) != ret.end()) {
    return ret[m];
  }
  if (m % 2 == 0) {
    return ret[m] = (solve(m / 2) + solve(m / 2 - 1)) % MOD;
  }
  return ret[m] = 1LL * solve(m / 2) * o % MOD;
}

int main() {
  scanf("%d%d", &n, &m);
  n -= 2;
  Matrix trans(3, 3);
  trans.v[1][3] = 1;
  trans.v[2][1] = 1;
  trans.v[2][3] = 1;
  trans.v[3][2] = 1;
  trans = qpow(trans, n - 1);
  Matrix init(1, 3);
  init.v[1][1] = 3;
  init.v[1][2] = 2;
  init.v[1][3] = 5;
  init = init * trans;
  o = init.v[1][1];
  printf("%d\n", solve(m));
}