#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
#define pb push_back
#define fs first
#define sn second
#define ms(a, x) memset(a, x, sizeof(a))
#define SZ(v) ((int) (v).size())
#define ALL(v) begin(v), end(v)
const int INF = 0x3f3f3f3f;
#define FR(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define FORR(i, a, b) for(int i = (a); i >= (b); i--)
#define dbg(x){cerr << #x << ' ' << (x) << endl;}
#define dbgArr(arr, n){cerr << #arr; FR(_i, n) cerr << ' ' << (arr)[_i]; cerr << endl;}
template <class T, class U>
ostream& operator<<(ostream &os, pair<T, U> p){return os << "(" << p.fs << ", " << p.sn << ")";}

const int MOD = 998244353;
const int MN = 3;

typedef array<array<int, MN>, MN> Mat;

ostream& operator<<(ostream &os, Mat mat){
    os << '\n';
    FR(i, MN) FR(j, MN) os << mat[i][j] << " \n"[j == MN-1];
    return os;
}

Mat operator*(const Mat &a, const Mat &b){
    Mat res = {};
    FR(i, MN) FR(j, MN) FR(k, MN) res[i][k] = (res[i][k] + (ll) a[i][j]*b[j][k]) % MOD;
    return res;
}

Mat operator-(const Mat &a, const Mat &b){
    Mat res = {};
    FR(i, MN) FR(j, MN){
        res[i][j] = a[i][j] - b[i][j];
        if(res[i][j] < 0) res[i][j] += MOD;
    }
    return res;
}

ll h(ll n) {
    Mat a{{{0,1,1},{1,0,0},{0,1,0}}};
    Mat c{{{1,0,0},{1,0,0},{0,0,0}}};
    for (; n > 0; n /= 2) {
        if (n % 2) {
            c = a * c;
        }
        a = a * a;
    }
    return c[2][0];
}

map<ll, ll> mf;

ll f(ll m, ll g){
    if (mf.count(m)) return mf[m];
    if (m % 2) {
        return mf[m] = g*f((m-1)/2, g)%MOD;
    } else {
        return mf[m] = (f(m/2,g)+f(m/2-1,g)) % MOD;
    }
}

ll g(ll n) {
    if (n == 3) return 3;
    return (h(n-1)+h(n-3)+2*h(n-4)) % MOD;
}

int main(){
    cin.sync_with_stdio(0); cin.tie(0);

    mf[0] = 1;
    ll n,m; cin>>n>>m;
    cout << f(m,g(n)) << "\n";
}