#include <bits/stdc++.h>
using namespace std;
int main() {
  double distance, traffic, speed, green, red;
  cin >> distance >> traffic >> speed >> green >> red;
  double time = 0.0;
  time += (traffic / speed);
  double temp1 = time;
  double temp2 = ((distance - traffic) / speed);
  double cnt = 0.0;
  for (int i = 0;; i++) {
    if (i % 2 == 0) cnt += green;
    if (i % 2 != 0) cnt += red;
    if (cnt > time && i % 2 == 0) {
      cout << fixed << setprecision(8) << temp1 + temp2;
      return 0;
    }
    if (cnt > time && i % 2 == 1) {
      cout << fixed << setprecision(8) << (temp1 + (cnt - time) + temp2);
      return 0;
    }
  }
}
