#include <bits/stdc++.h>
using namespace std;
long double l, d, v, g, r;
int main() {
  cin >> l >> d >> v >> g >> r;
  long double t1 = (d / v);
  int a = t1 / (g + r);
  long double t2 = t1 - a * (g + r);
  if (t2 >= g) t1 = (a + 1) * (g + r);
  t1 += (l - d) / v;
  cout << setprecision(6) << fixed << t1 << endl;
  return 0;
}
