#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  long double l, d, v, g, r, t1, t;
  cin >> l >> d >> v >> g >> r;
  t = l / v;
  t1 = d / v;
  int n = (t1 + r) / (r + g);
  if (t1 <= n * (g + r)) t += n * (g + r) - t1;
  cout << setprecision(13) << fixed << t;
}
