#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi  = vector<int>; using vb  = vector<bool>; using vd  = vector<double>; using vl  = vector<ll>;
using vvi = vector<vi>;  using vvb = vector<vb>;   using vvd = vector<vd>;     using vvl = vector<vl>;

#define REP(i,n) for(ll i=0; i<(n); ++i)
#define FOR(i,b,n) for(ll i=(b); i<(n); ++i)
#define ALL(v) (v).begin(), (v).end()
#define TEN(x) ((ll)1e##x)

int main() {
	// cin.tie(0);
	// ios_base::sync_with_stdio(false);
	cout << fixed << setprecision(5);
	ll h, a, d;
	cin >> h >> a >> d;
	vd expect(TEN(4)*2 + 1, TEN(4) * 2+1); expect[0] = 0;
	REP(i, expect.size()) {
		if (i + a < expect.size()) expect[i + a] = min(expect[i + a], expect[i] + 1);
		if (i + d < expect.size()) expect[i + d] = min(expect[i + d], expect[i] + 1.5);
	}

	double v = TEN(4)*2+1;
	FOR(i, h, expect.size()) v = min(v, expect[i]);	
	cout << v << endl;
	return 0;
}