#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<unordered_map>
#define rep(i, a, b) for(int i = (a); i <= (b); i++)
#define per(i, a, b) for(int i = (a); i >= (b); i--)
using namespace std;
typedef long long ll;
const ll mod = 998244353;
ll coef;

unordered_map<int, ll> mp;
ll dfs(int x){
	if(!x) return 1; 
	if(mp.count(x)) return mp[x];
	if(x & 1) return mp[x] = coef * dfs(x>>1) % mod;
	else return (dfs(x>>1) + dfs((x>>1)-1)) % mod;
}

struct matrix{
	ll a[3][3];
	matrix(int x = 0){
		memset(a, 0, sizeof(a));
		a[0][0] = a[1][1] = a[2][2] = x;
	}
	matrix(const vector<int> &x){
		rep(i, 0, 2) rep(j, 0, 2) a[i][j] = x.at(i*3+j);
	}	
	ll* operator [] (const int &x) {return a[x];}
	const ll* operator [] (const int &x) const {return a[x];}
	matrix operator * (const matrix &x) const {
		matrix ret;
		rep(i, 0, 2) rep(k, 0, 2) rep(j, 0, 2)
			(ret[i][j] += a[i][k] * x[k][j]) %= mod;
		return ret;
	}
};
matrix qpow(matrix x, ll y){
	matrix ret = 1;
	for(; y; y >>= 1, x = x * x) if(y & 1) ret = ret * x;
	return ret;
}
matrix B({0, 1, 1, 1, 0, 0, 0, 1, 0});

int n, m;
int main(){
	scanf("%d%d", &n, &m);
	B = qpow(B, n);
	coef = (B[0][0] + B[1][1] + B[2][2]) % mod;
	printf("%lld\n", dfs(m));
	return 0;
}