#include <bits/stdc++.h>
using namespace std;
void __print(long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  long long f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
signed main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  cout << fixed << setprecision(10);
  long long l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double time = 0;
  double time_for_d = (double)d / v;
  long long flg = 0;
  double wait = 0;
  long long rplusg = floor(time_for_d) / (r + g);
  if (time_for_d < rplusg * (r + g) + g)
    flg = 1;
  else
    flg = 0, wait = rplusg * (r + g) + g + r - time_for_d;
  cout << (double)l / v + wait;
  return 0;
}
