#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double ans = 0;
  int time1 = d / (v * (g + r));
  if (d < (time1 * (r + g) + g) * v)
    ans += (double)d / v;
  else
    ans += (time1 + 1) * (r + g);
  ans += (double)(l - d) / v;
  cout.precision(8);
  cout << fixed << ans << endl;
  return 0;
}
