#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double ans = (1.0 * l) / (v * 1.0), tl = (1.0 * d) / (1.0 * v), rem;
  rem = fmod(tl, 1.0 * (g + r));
  if (rem - g >= 0.0) ans += (r + g * 1.0 - rem);
  cout << setprecision(8) << ans << endl;
  return 0;
}
