#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <tuple>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;

class BallsInBoxes { public:
	long long maxTurns(long long N, long long K)
	{
		if(N < 2*K)
			return shortCase(N, K);
		if(N < 3*K)
			return 1 + shortCase((N+K)/2, K);
		if(N < 10*K)
			return 1 + maxTurns(N-K, K);
		return (N/K-4) + maxTurns(N - (N/K-4)*K, K);
	}

	LL shortCase(LL N, LL K) {
		// The case where N is small enough and all positions are possoible.
		return solve(N-K);
	}

	LL solve(LL N) {
		// Determine what number in [0,N] out of N boxes are filled.
		return N ? solve(N/2)+1 : 0;
	}
};

// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
 { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
 { os << "{ ";
   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const long long& Expected, const long long& Received) {
 bool ok = (Expected == Received);
 if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
 cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END	 verify_case(_, BallsInBoxes().maxTurns(N, K));}
int main(){

CASE(0)
	long long N = 10LL; 
	long long K = 10LL; 
	long long _ = 0LL; 
END
CASE(1)
	long long N = 100LL; 
	long long K = 1LL; 
	long long _ = 99LL; 
END
CASE(2)
	long long N = 1000LL; 
	long long K = 999LL; 
	long long _ = 1LL; 
END
CASE(3)
	long long N = 10LL; 
	long long K = 5LL; 
	long long _ = 3LL; 
END
CASE(4)
	long long N = 1234567898765LL; 
	long long K = 658167578LL; 
	long long _ = -1LL;
END
/*
CASE(5)
	long long N = LL; 
	long long K = LL; 
	long long _ = LL; 
END
*/
}
// END CUT HERE
