#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>

using namespace std;

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>


ll a, b, c;
double ans = 1e9;
int main() {
	cin >> a >> b >> c;
	REP(i, INF) {
		if (i * b >= a) {
			ans = min(ans, (double)i);
			break;
		}
		ll now = (a - i * b + c - 1) / c;
		double nd = (double)now / 2 * 3;
		ans = min(ans, i + nd);
	}
	cout << fixed << ans << endl;
}