#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>
#include <random>

#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for (int (i) = (a) - 1; (i) >= 0; (i)--)
#define FORR(i, a, b) for (int (i) = (a) - 1; (i) >= (b); (i)--)
#define PI acos(-1.0)
#define DEBUG(C) cerr << C << endl;
#define VI vector <int>
#define VII vector <VI>
#define VL vector <LL>
#define VLL vector <VL>
#define VD vector <double>
#define VDD vector <VD>
#define PII pair <int, int>
#define PDD pair <double, double>
#define PLL pair <LL, LL>
#define VPII vector <PII>
#define ALL(a) (a).begin(), (a).end()
#define SORT(a) sort(ALL(a))
#define REVERSE(a) reverse(ALL(a))
#define MP make_pair
#define EB emplace_back
#define FORE(a, b) for (auto &&a : b)
#define FIND(s, n) (s.find(n) != s.end())

using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

double dp[10010];
int main(void) {
	int H, A, D;
	cin >> H >> A >> D;
	REP(i, 10010) dp[i] = INF;
	dp[0] = 0;
	FOR(i, 1, H + 1) {
		if (i - A >= 0) dp[i] = min(dp[i - A] + 1, dp[i]);
		else dp[i] = min(dp[i], 1.0);
		if (i - D >= 0) dp[i] = min(dp[i], dp[i - D] + 1.5);
		else dp[i] = min(dp[i], 1.5);
	}
	cout << fixed << setprecision(10) << dp[H] << endl;
}