#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<cmath>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<numeric>
#include<functional>
#include<complex>

using namespace std;
#define BET(a,b,c) ((a)<=(b)&&(b)<(c))
#define FOR(i,n) for(int i=0,i##_end=(int(n));i<i##_end;i++)
#define SZ(x) (int)(x.size())
#define ALL(x) (x).begin(),(x).end()
#define MP make_pair
#define FOR_EACH(it,v) for(__typeof(v.begin()) it=v.begin(),it_end=v.end() ; it != it_end ; it++)
typedef vector<int> VI;
typedef vector<VI> VVI;

int main()
{
    int H,A,D;
    cin>>H>>A>>D;
    vector<double> dp(H+1);
    dp[0] = 0 ;
    for(int i=1;i<=H;i++){
        dp[i] = 1;
        if(i - A >= 0) dp[i] = dp[i - A] + 1;
        
        double waza = 0;
        if(i - D >= 0) waza = dp[i - D];
        // v = waza * 2 / 3 + v / 3 + 1
        // 2 * v = 2 * waza + 3
        // v = waza + 3 / 2
        dp[i] = min(dp[i], waza + 1.5);
    }
    printf("%.10f\n", dp[H]);
    return 0;
}