#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, t, i;
  int g, r;
  cin >> l >> d >> v >> g >> r;
  t = d / v;
  for (i = 0; t > g + r;) {
    t -= g + r;
    i += g + r;
  }
  if (t > g - 1e-9)
    i += g + r;
  else
    i += t;
  cout << fixed << setprecision(11) << i + (l - d) / v << endl;
}
