#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <queue>
#include "math.h"
#include <complex>
#include <iomanip>
#include <map>
#define ifor(i,a,b) for (int i=(a);i<(b);i++)
#define rfor(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define rep(i,n) for (int i=0;i<(n);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
using namespace std;
typedef long double ld;
typedef long long int  lli;
typedef complex <double> P;
const double eps = 1e-11;
int vex[4]={1,0,-1,0};
int vey[4]={0,1,0,-1};
typedef vector<double> Vec;
typedef vector<int> vec;
typedef vector<Vec> MAT;
typedef vector<vec> mat;
lli MOD=1000000007;
  int H,A,D;
 int main(){
   cin >> H >> A >> D;
  int a,d=0; 
  a = H/A;//a+1の期待値で殴れる
  double ans = (double)a+1.0;
  while(a>=0){
      while(a*A+d*D<H)d++;
      ans = min(ans,a+d*1.5);
      a--;
  }
  cout << ans << endl;
 }