#include <bits/stdc++.h>
using namespace std;
struct camel {
  int pos;
  int tof;
};
int main() {
  cout << setprecision(8) << fixed;
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double temp;
  double T;
  temp = d / v;
  double q;
  bool yer = 1;
  while (temp >= 0) {
    if (yer) {
      temp -= g;
      T = 0;
      yer = !yer;
    } else {
      T = r - temp;
      temp -= r;
      yer = !yer;
    }
  }
  cout << ((l / v) + T);
}
