#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	int h, a, d;
    cin>>h>>a>>d;
    double dp[10010];
    dp[0]=0;
    for(int i=1; i<=h; i++){
        dp[i]=min(dp[max(0, i-a)]+1, dp[max(0, i-d)]+1.5);
    }
    printf("%.3lf\n", dp[h]);
	return 0;
}