#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double time;
  time = 1.0 * d / v;
  double indication = (int)time % (g + r) + time - (int)time;
  if (indication > g || fabs(indication - g) < 10e-7)
    time += g + r - indication;
  cout << setprecision(8) << time + (l - d) * 1.0 / v;
  return 0;
}
