#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,k;
	cin>>n>>k;
	if(n<=k) cout<<2;
	else if(n*2%k==0) cout<<(n*2)/k;
	else cout<<(n*2)/k+1;
	return 0;
}
/**************************************************************
	Problem: 2004
	User: admin
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/