#include<iostream>
#include<iomanip>
#include<algorithm>
using namespace std;
int H,A,D;
double dp[1<<17];
main()
{
	cin>>H>>A>>D;
	for(int i=1;i<=H;i++)
	{
		dp[i]=min(1+(i>=A?dp[i-A]:0),1.5+(i>=D?dp[i-D]:0));
	}
	cout<<fixed<<setprecision(15)<<dp[H]<<endl;
}