//URL:https://yukicoder.me/problems/no/23

#include <iostream>
#define FOR(i,s,e) for(int i = (s);i <= (e);i++)
using namespace std;

int H,A,D;

double res = 100000;

int main()
{
	cout << fixed;
	cin >> H >> A >> D;
	int maxN = H / A;
	if(H % A != 0) maxN++;
	FOR(i,0,maxN)
	{
		int now = H - A * i;
		double cou = i;
		if(now > 0)
		{
			int need = now / D;
			if(now % D != 0) need++;
			cou += static_cast<double>(1.5 * need);
		}
		res = min(res,cou);
	}
	cout << res << endl;

	return 0;
}