/*

              ∧∧∩ 
             ( ゚∀゚)/ キタ━━━━━━(゚∀゚)━━━━━━!!!!  
            ⊂   ノ  ゆっくり見てってね!!!!!!!!
             (つ ノ
    o          (ノ
     \      ☆
             |      o
          (⌒ ⌒ヽ   /     ☆
    \  (´⌒  ⌒  ⌒ヾ   /
      ('⌒ ; ⌒   ::⌒  )
     (´     )     ::: ) /
  ☆─ (´⌒;:    ::⌒`) :;  )

*/
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

bool printb(bool f) {
	if (f) cout << "Yes\n";
	else cout << "No\n";
	return f;
}

#define elif else if
#define rep(i, s, n) for (int i = (s); i < (int)(n); i++)
#define all(a) a.begin(), a.end()
// xを2進数にした際にi桁目が0か1か
#define bit(x,i)((x>>i)&1)
typedef long long ll;
typedef long double ld;

ld pi = 3.14159265358979;

inline void scan(){}
template<class Head,class... Tail>
inline void scan(Head&head,Tail&... tail){std::cin>>head;scan(tail...);}
 
// print(a, b, c) => cout << a << ' ' << b << ' ' << c << endl;
inline void print(){}
template<class Head,class... Tail>
inline void print(Head&head,Tail&... tail){std::cout<<head<<" ";print(tail...);cout<<endl;}

//vectorのcout,cin
template<typename T>
std::istream &operator>>(std::istream&is,std::vector<T>&v){for(T &in:v){is>>in;}return is;}
template<typename T>
std::ostream &operator<<(std::ostream&os,const std::vector<T>&v){for(auto it=std::begin(v);it!=std::end(v);){os<<*it<<((++it)!=std::end(v)?" ":"");}return os;}

// 2地点の距離(long double)
long double coor_dist(long double xi, long double yi, long double xj, long double yj) {
    return sqrt(abs((xi - xj) * (xi - xj)) + abs((yi - yj) * (yi - yj)));
}

// 回文かどうかの判定
bool iskaibun(string s){ll k = s.size();rep(i,0,k/2){if(s[i]!=s[k-1-i]){return false;}}return true;}







int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll h, a; cin >> h >> a;

    ll ans = 0;
    ll cnt = 1;
    while(h > 0) {
        h /= a;
        ans += cnt;
        cnt *= 2;
    }
    cout << ans << endl;
}