#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)



int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int h, a, d;
    cin >> h >> a >> d;
    vector<double> e;

    rep(i, (h + a - 1) / a)
        e.push_back( ((h - a * i) + d - 1) / d * 1.5);
    
    rep(i, e.size())
        e[i] += i;
    e.push_back((h + a - 1) / a);

    cout << *min_element(e.begin(), e.end()) << endl;


    return 0;
}