#include<bits/stdc++.h>
#define ll long long
using namespace std;
typedef array<array<ll,3>,3> Mat;
const int MOD=998244353;
Mat operator *(const Mat &u,const Mat &v) {
	Mat w{0,0,0, 0,0,0, 0,0,0};
	for(int i:{0,1,2}) for(int k:{0,1,2}) for(int j:{0,1,2}) w[i][j]=(w[i][j]+u[i][k]*v[k][j])%MOD;
	return w;
}
signed main() {
	int n,m;
	scanf("%d%d",&n,&m);
	Mat I{1,0,0, 0,1,0, 0,0,1},T{0,1,1, 1,0,0, 0,1,0};
	for(int k=n;k;k>>=1,T=T*T) if(k&1) I=I*T;
	ll Z=(I[0][0]+I[1][1]+I[2][2])%MOD;
	unordered_map <int,ll> dp;
	function<ll(int)> f=[&](int x) {
		if(x<=1) return x?Z:1;
		if(dp.count(x)) return dp[x];
		if(x&1) return dp[x]=Z*f(x/2)%MOD;
		return dp[x]=(f(x/2)+f(x/2-1))%MOD;
	};
	printf("%lld\n",f(m));
	return 0;
}