#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    double l, d, v, g, r;
    cin >> l >> d >> v >> g >> r;
    double ans = d / v;
    double temp = ans;
    while (temp >= g + r) temp -= (g + r);
    if (temp >= g) ans += (g + r - temp);
    ans += (l - d) / v;
    cout << fixed << setprecision(7) << ans << '\n';
  }
  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " sec \n";
  return 0;
}
