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