#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define inf INT_MAX
#define fr(i,l,r) for (i=(l); i<=(r); i++)
#define rfr(i,l,r) for (i=(l); i>=(r); i--)
template<typename T>inline void read(T &n){
    T w=1; n=0; char ch=getchar();
    while (!isdigit(ch) && ch!=EOF){ if (ch=='-') w=-1; ch=getchar(); }
    while (isdigit(ch) && ch!=EOF){ n=(n<<3)+(n<<1)+(ch&15); ch=getchar(); }
    n*=w;
}
template<typename T>inline void write(T x){
    if (x==0){ putchar('0'); return ; }
    T tmp;
    if (x>0) tmp=x;
    else tmp=-x;
    if (x<0) putchar('-');
    char F[105];
    long long cnt=0;
    while (tmp){
        F[++cnt]=tmp%10+48;
        tmp/=10;
    }
    while (cnt) putchar(F[cnt--]);
}
#define Min(x,y) x = min(x,y)
#define Max(x,y) x = max(x,y)
//基础配置=================================================================================
const ll mod = 998244353;
ll n,m,bsv;
struct matrix{
    ll a[4][4];
    void clear(){
        memset(a,0,sizeof(a));
    }
};
matrix operator * (const matrix x,const matrix y){
    matrix ans; ans.clear();
    ll i,j,k;
    fr(i,0,3)
        fr(j,0,3)
            fr(k,0,3)
                ( ans.a[i][k] += x.a[i][j] * y.a[j][k] ) %=mod;
    return ans;
}
matrix trs;
matrix pw(matrix x,ll y){
    matrix ans = x; y--;
    while (y){
        if (y&1) ans = ans*x;
        x = x*x;
        y >>= 1;
    }
    return ans;
}
ll calc(ll n){
    trs.clear();
    trs.a[1][2] = 1;
    trs.a[1][3] = 1;
    trs.a[2][1] = 1;
    trs.a[3][2] = 1;
    matrix st; ll ans = 0;
    //01
    st.clear();
    st.a[1][1] = 1;
    st = st*pw(trs,n-2);
    ( ans += st.a[1][1] + st.a[1][3] ) %=mod;
    //10
    st.clear();
    st.a[1][2] = 1;
    st = st*pw(trs,n-2);
    ( ans += st.a[1][1] + st.a[1][2] ) %=mod;
    //11
    st.clear();
    st.a[1][3] = 1;
    st = st*pw(trs,n-2);
    ( ans += st.a[1][2] ) %=mod;
    return ans;
}
map<ll,ll> mp;
ll solve(ll m){
    if (m==0) return 1;
    if (mp.count(m)) return mp[m];
    if (m&1) return mp[m] = bsv*solve(m>>1) %mod;
    else return mp[m] = ( solve(m>>1) + solve((m-1)>>1) ) %mod;
}
int main(){
	// freopen("a.in","r",stdin);
//	freopen(".out","w",stdout);
    read(n); read(m);
    bsv = calc(n);
    write((solve(m)%mod+mod)%mod);
    return 0;
}
//g++ a.cpp -o a -Wall -Wl,--stack=512000000 -std=c++11 -O2