#include <bits/stdc++.h>
using namespace std;
const int INF = 100000;
int main(){
  int H, A, D;
  cin >> H >> A >> D;
  double ans = INF;
  for (int i = 0; i <= (H + A - 1) / A; i++){
    ans = min(ans, i + (H - A * i + D - 1) / D * 1.5);
  }
  cout << ans << endl;
}