#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:64000000");
using namespace std;
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T abs(T x) {
  return x < 0 ? -x : x;
}
const double EPS = 1e-9;
const int INF = 1000000000 + 7;
const long long LINF = INF * 1LL * INF * 1LL;
const double PI = 3.1415926535897932384626433832795;
int l, d, v;
double g, r;
int main() {
  ios_base::sync_with_stdio(false);
  cin >> l >> d >> v >> g >> r;
  double t1 = double(d * 1. / v * 1.);
  double t = 0;
  bool ok = 1;
  while (t1 >= t) {
    t += g;
    ok = 1;
    if (t1 >= t) {
      t += r;
      ok = 0;
    }
  }
  cout << fixed;
  if (ok) {
    cout << setprecision(6) << double(l) / double(v) << endl;
  } else {
    cout << setprecision(6) << t * 1. + double((l * 1. - d * 1.) * 1. / v * 1.);
  }
  return 0;
}
