#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef double db;
ll H,A,D;
db dp[10001];
db rec(ll h){
	if(h<=0) return 0;
	if(dp[h]>0) return dp[h];
	db res=min(rec(h-A)+1,rec(h-D)+1.5);
	return dp[h]=res;
}

int main()
{
	cin>>H>>A>>D;
	printf("%lf\n",rec(H));
}