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