#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

using Real = double;

int H, A, D;
vector<Real> dp;
Real dfs(int h) {
	if (h <= 0) return 0;
	Real res = 1e18;
	chmin(res, dfs(h - A) + 1);
	chmin(res, dfs(h - D) + 1.5);
	return dp[h] = res;
}

int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/
	cin >> H >> A >> D;
	dp.resize(H + 1, -inf);
	cout << fixed << setprecision(12) << dfs(H) << endl;
	return 0;
}