#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r, x;
  cin >> l;
  cin >> d;
  cin >> v;
  cin >> g;
  cin >> r;
  if (d / v < g)
    cout.precision(8), cout << l / v;
  else
    cout.precision(8), cout << ceil(d / v / (g + r)) * (g + r) + (l - d) / v;
  return 0;
}
