#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-9;
int main() {
  long double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  long double t = d / v;
  long double green = 0., leftGreen = 0., rightGreen = 0.;
  while (true) {
    leftGreen = green, rightGreen = green + g;
    if (t < rightGreen) {
      break;
    }
    green += g + r;
  }
  t = max(t, leftGreen);
  t += (l - d) / v;
  cout << fixed << setprecision(15) << t << endl;
  return 0;
}
