#include <cstdio>
#include <cstring>
#include <algorithm>

#define int long long

using namespace std;

const int mod = 998244353;

int n, m, sum, f[35][2];

struct Matrix
{
    int c[3][3];
    Matrix()
    {
        memset(c, 0, sizeof(c));
    }
    friend Matrix operator * (Matrix x, Matrix y)
    {
        Matrix a;
        for(int i = 0; i < 3; ++ i)
            for(int j = 0; j < 3; ++ j)
                for(int k = 0; k < 3; ++ k)
                    (a.c[i][j] += x.c[i][k] * y.c[k][j]) %= mod;
        return a;
    }
    friend Matrix operator ^ (Matrix x, int y)
    {
        Matrix r;
        for(int i = 0; i < 3; ++ i)
            r.c[i][i] = 1;
        for(; y; y >>= 1, x = x * x)
            if(y & 1)
                r = r * x;
        return r;
    }
};

Matrix A, B;

signed main()
{
    scanf("%lld%lld", &n, &m);
    B.c[0][1] = B.c[1][0] = B.c[1][2] = B.c[2][0] = 1;

    B = B ^ n - 3;
    A.c[0][0] = 1;
    A = A * B;
    sum = (sum + A.c[0][0]) % mod;

    memset(A.c, 0, sizeof(A.c));
    A.c[0][0] = A.c[0][2] = 1;
    A = A * B;
    sum = (sum + A.c[0][1] + A.c[0][2]) % mod;

    memset(A.c, 0, sizeof(A.c));
    A.c[0][1] = 1;
    A = A * B;
    sum = (sum + A.c[0][0] + A.c[0][1]) % mod;

    if(m & 1)
        f[0][0] = sum;
    else
        f[0][0] = f[0][1] = 1;
    for(int i = 1; i < 31; ++ i)
    {
        if(m >> i & 1)
        {
            f[i][0] = (f[i - 1][0] * sum + f[i - 1][1]) % mod; 
            f[i][1] = f[i - 1][1];
        }
        else
        {
            f[i][0] = f[i - 1][0];
            f[i][1] = (f[i - 1][0] + f[i - 1][1] * sum) % mod;
        }
    }
    printf("%lld\n", f[30][0]);

    return 0;
}