#include <bits/stdc++.h>
using namespace std;
signed main() {
  long double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  long double ans = 0;
  ans = d / v;
  long double t = ans;
  while (g + r <= t) t = t - g - r;
  if (t >= g) ans += g + r - t;
  ans += (l - d) / v;
  cout << fixed << setprecision(8) << ans;
}
