#include <iostream>
#include <cmath>
#include <vector>
#include <utility>
#include <queue>
#include <map>
#include <string>
#include <cstring>
#include <list>
#include <algorithm>
#define INF 114514
using namespace std;

typedef pair<double,double> P;
typedef long long ll;

int a,d;
double memo[100001];
double dfs(int h){
	if(h <= 0)return 0;
	if(memo[h] != -1)return memo[h];
	return memo[h] = min(dfs(h-a) + 1 ,dfs(h-d) + 1.5);
}

int main(void) {
	int h;
	for(int i=0;i<100001;i++)memo[i] = -1;
	cin >> h >> a >> d;
	printf("%.10f\n",dfs(h));
}

//command ctrl 上下
//command D
//command caps G → '' ""