#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <string>
#include <queue>
#include <map>
#include <bitset>
#include <set>
#include <stack>
#include <numeric>
#include <unordered_map>
#include <random>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vd = vector<double>;
using vs = vector<string>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
using vpii = vector<pii>;
using vpll = vector<pll>;
using vpdd = vector<pdd>;
const int inf = (1 << 30) - 1;
const ll INF = 1LL << 60;
const int MOD = 1000000007;
//const int MOD = 998244353;

int main() {
	int h, a, d;
	cin >> h >> a >> d;
	vd dp(h + 1, inf);
	dp[h] = 0;
	for (int i = h; i >= 1; i--) {
		if (dp[i] == inf) continue;
		int x = max(0, i - a);
		dp[x] = min(dp[x], dp[i] + 1);
		x = max(0, i - d);
		dp[x] = min(dp[x], dp[i] + 1.5);
	}
	cout << fixed << setprecision(3);
	cout << dp[0] << endl;
	
	return 0;
}