#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double time_to_tr = d / v;
  double cur_time = 0.00;
  bool red = 0;
  double before = 0.00;
  bool isred;
  while (1) {
    before = cur_time;
    isred = red;
    if (red) {
      cur_time += r;
    } else {
      cur_time += g;
    }
    red ^= 1;
    if (cur_time > time_to_tr) break;
  }
  if (isred) time_to_tr = before + r;
  double ans = time_to_tr + (l - d) / v;
  cout << fixed << setprecision(10) << ans << endl;
  return 0;
}
