#include<iostream>
#include<math.h>
#include<algorithm>
#include<stdint.h>
#include<vector>
#include<deque>
#include<stack>
#include<functional>
#include<string>
#include<numeric>
#include<cstring>
#include<random>
#include<array>
#include<fstream>
#include<iomanip>
#include<list>
#include<set>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<queue>

/*
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
*/

using namespace std;

using ll = long long;
using ull = unsigned long long;

#define REP(i,a,b) for(ll i = a; i < b; ++i)
#define PRI(s) std::cout << s << endl
#define PRIF(v, n) printf("%."#n"f\n", (double)v)

template<typename A, typename B>void mins(A& a, const B& b) { a = min(a, (A)b); };
template<typename A, typename B>void maxs(A& a, const B& b) { a = max(a, (A)b); };


int main() {
	ll H, A, D; cin >> H >> A >> D;
	vector<double> dp(H + 1);
	dp[0] = 0;
	REP(i, 1, H + 1) {
		double a = (i - A >= 0 ? 1 + dp[i - A] : 1);
		double d = (i - D >= 0 ? 1.5 + dp[i - D] : 1.5);
		dp[i] = min(a,d);
	}
	PRIF(dp[H], 12);
	return 0;
}