#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r, t;
  cin >> l >> d >> v >> g >> r;
  if (fmod(d / v, r + g) < g) {
    cout << fixed << setprecision(9) << l / v;
  } else {
    cout << fixed << setprecision(9) << l / v + ((r + g) - fmod(d / v, r + g));
  }
  return 0;
}
