#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  for (int i = 0;; i += g + r) {
    if (d * 1.0 / v < i + g) {
      cout << fixed << max(i * 1.0, (d * 1.0 / v)) + (l - d) * 1.0 / v;
      break;
    }
  }
  return 0;
}
