#include <bits/stdc++.h>
using namespace std;
void Solve() {
  long long l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double t = (l * 1.0) / v, tmp = (d * 1.0) / v;
  long long sign = 1, time = 0;
  while (time <= tmp) {
    if (sign == 1)
      time += g;
    else
      time += r;
    sign = !sign;
  }
  if (sign == 1) t += (time - tmp);
  cout << setprecision(13) << t << endl;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  Solve();
  return 0;
}
