#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(8);
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double t = d / v;
  int time = 0;
  bool x = true;
  while (time < t) {
    if (x)
      time += g;
    else
      time += r;
    x = !x;
  }
  if (fabs(time - t) <= 0.0000001) {
    if (x)
      cout << l / v << endl;
    else {
      double ans = t + r + (l - d) / v;
      cout << ans << "\n";
    }
  } else {
    if (x) {
      double ans = t + (time - t) + (l - d) / v;
      cout << ans << "\n";
    } else {
      cout << l / v << endl;
    }
  }
}
