#include <bits/stdc++.h>

/**
 * @title Modint
 * @docs mint.md
 */
template <int32_t M> class ModInt{
public:
  constexpr static int32_t MOD = M;
  uint32_t val;
  
  constexpr ModInt(): val(0){}
  constexpr ModInt(int64_t n){
    if(n >= M) val = n % M;
    else if(n < 0) val = n % M + M;
    else val = n;
  }
  
  constexpr auto& operator=(const ModInt &a){val = a.val; return *this;}
  constexpr auto& operator+=(const ModInt &a){
    if(val + a.val >= M) val = (uint64_t)val + a.val - M;
    else val += a.val;
    return *this;
  }
  constexpr auto& operator-=(const ModInt &a){
    if(val < a.val) val += M;
    val -= a.val;
    return *this;
  }
  constexpr auto& operator*=(const ModInt &a){
    val = (uint64_t)val * a.val % M;
    return *this;
  }
  constexpr auto& operator/=(const ModInt &a){
    val = (uint64_t)val * a.inv().val % M;
    return *this;
  }

  constexpr auto operator+(const ModInt &a) const {return ModInt(*this) += a;}
  constexpr auto operator-(const ModInt &a) const {return ModInt(*this) -= a;}
  constexpr auto operator*(const ModInt &a) const {return ModInt(*this) *= a;}
  constexpr auto operator/(const ModInt &a) const {return ModInt(*this) /= a;}
  
  constexpr bool operator==(const ModInt &a) const {return val == a.val;}
  constexpr bool operator!=(const ModInt &a) const {return val != a.val;}
  
  constexpr auto& operator++(){*this += 1; return *this;}
  constexpr auto& operator--(){*this -= 1; return *this;}
  
  constexpr auto operator++(int){auto t = *this; *this += 1; return t;}
  constexpr auto operator--(int){auto t = *this; *this -= 1; return t;}
  
  constexpr static ModInt power(int64_t n, int64_t p){
    if(p < 0) return power(n, -p).inv();
    
    int64_t ret = 1, e = n % M;
    for(; p; (e *= e) %= M, p >>= 1) if(p & 1) (ret *= e) %= M;
    return ret;
  }
  
  constexpr static ModInt inv(int64_t a){
    int64_t b = M, u = 1, v = 0;
    
    while(b){
      int64_t t = a / b;
      a -= t * b; std::swap(a,b);
      u -= t * v; std::swap(u,v);
    }
    
    u %= M;
    if(u < 0) u += M;
    
    return u;
  }
  
  constexpr static auto frac(int64_t a, int64_t b){return ModInt(a) / ModInt(b);}
  
  constexpr auto power(int64_t p) const {return power(val, p);}
  constexpr auto inv() const {return inv(val);}
  
  friend constexpr auto operator-(const ModInt &a){return ModInt(M-a.val);}
  
  friend constexpr auto operator+(int64_t a, const ModInt &b){return ModInt(a) + b;}
  friend constexpr auto operator-(int64_t a, const ModInt &b){return ModInt(a) - b;}
  friend constexpr auto operator*(int64_t a, const ModInt &b){return ModInt(a) * b;}
  friend constexpr auto operator/(int64_t a, const ModInt &b){return ModInt(a) / b;}
  
  friend std::istream& operator>>(std::istream &s, ModInt<M> &a){s >> a.val; return s;}
  friend std::ostream& operator<<(std::ostream &s, const ModInt<M> &a){s << a.val; return s;}

  template <int N>
  static auto div(){
    static auto value = inv(N);
    return value;
  }

  explicit operator int32_t() const noexcept {return val;}
  explicit operator int64_t() const noexcept {return val;}
};



namespace solver{
  using mint = ModInt<998244353>;
  
  void solve(){
    int64_t N, L; std::cin >> N >> L;

    auto ans = mint::power(2, (N + L - 1) / L) - 1;
    std::cout << ans << "\n";
  }
}

int main(){
  solver::solve();
  return 0;
}