#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using ll = long long;
int h,a,d;
ll dp[30000];
const ll INF = LLONG_MAX/3;

void solve(){
	for(int i = 0;i<30000;i++)dp[i] = INF;
	dp[0] = 0;
	for(int i = 0;i<30000;i++){
		if(i+a<30000)
			dp[i+a] = min(dp[i+a],dp[i]+2);
		if(i+d<30000)
			dp[i+d] = min(dp[i+d],dp[i]+3);
	}
	ll ans = INF;
	for(int i = h;i<30000;i++){
		ans = min(dp[i],ans);
	}
	printf("%.10lf\n",ans/2.0);
}

signed main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cin >> h >> a >> d;
	solve();
}