#include <bits/stdc++.h>
using namespace std;

int main() {
  int H, A, D;
  cin >> H >> A >> D;
  double ans = 1e9;
  for (int a = 0; a <= (H + A - 1) / A; a++) {
    double tmp = a;
    int h = H - A * a;
    if (h <= 0) {
      ans = min(ans, tmp);
      continue;
    }
    tmp += (h + D - 1) / D * 1.5;
    ans = min(ans, tmp);
  }
  cout << ans << "\n";
}