#include <bits/stdc++.h>
#include <atcoder/all>

namespace neguse {}
using namespace std;
using namespace atcoder;
using namespace neguse;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ld> vld;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<string> vs;
typedef vector<pii> vpii;
typedef vector<pll> vpll;

#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define _rrep(i,n) rrepi(i,n-1,-1)
#define rrepi(i,a,b) for(int i=int(a);i>int(b);--i)
#define rrep(...) _overload3(__VA_ARGS__,rrepi,_rrep)(__VA_ARGS__)
#define _each1(i,v) for(auto& i:v)
#define _each2(i,j,v) for(auto& [i,j]:v)
#define each(...) _overload3(__VA_ARGS__,_each2,_each1,)(__VA_ARGS__)

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define SORT(x) sort(all(x))
#define RSORT(x) sort(rall(x))
#define REVERSE(x) reverse(all(x))

#define dump(x) cerr << #x << " = " << (x) << '\n'
#define print(x) cout << (x) << '\n'
#define yes(f) cout << ((f) ? "Yes" : "No") << '\n'

#define ge(v, x) (int)(lower_bound(all(v), x) - v.begin())
#define gt(v, x) (int)(upper_bound(all(v), x) - v.begin())
#define le(v, x) (int)(upper_bound(all(v), x) - v.begin())-1
#define lt(v, x) (int)(lower_bound(all(v), x) - v.begin())-1

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

ostream& operator<<(ostream& os, const modint998244353& a) { return os << a.val(); }
ostream& operator<<(ostream& os, const modint1000000007& a) { return os << a.val(); }

template<class T> istream& operator>>(istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }
template<class T> ostream& operator<<(ostream& os, const vector<T>& vec) { for (const T& x : vec) os << x << ' '; return os; }


int main() {
    ll N;
    cin >> N;

    int K;
    cin >> K;

    using mint = modint998244353;
    vector<mint> fact(K + 1), ifact(K + 1);
    fact[0] = 1;
    rep(i, K) fact[i + 1] = fact[i] * (i + 1);
    rep(i, K + 1) ifact[i] = 1 / fact[i];
    auto comb = [&](int n, int k) {
        if (n < k || n < 0 || k < 0) return mint(0);
        return fact[n] * ifact[k] * ifact[n - k];
    };

    using mat = vector<vector<mint>>;
    mat M = mat(K + 2, vector<mint>(K + 2));
    rep(r, K + 1) rep(t, r + 1) M[r][K - t] = comb(r, t);
    M[K + 1][K] = M[K + 1][K + 1] = 1;

    auto mul = [&](const mat& A, const mat& B) {
        mat C(K + 2, vector<mint>(K + 2));
        rep(i, K + 2) rep(j, K + 2) rep(k, K + 2) C[i][j] += A[i][k] * B[k][j];
        return C;
    };

    auto pow = [&](mat A, ll n) {
        mat B(K + 2, vector<mint>(K + 2));
        rep(i, K + 2) B[i][i] = 1;
        while (n) {
            if (n & 1) B = mul(B, A);
            A = mul(A, A);
            n >>= 1;
        }
        return B;
    };

    M = pow(M, N - 1);
    mint ans = 0;
    rep(i, K + 2) ans += M[K + 1][i];
    cout << ans.val() << endl;
}