#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long double a, b, c, d, e;
  cin >> a >> b >> c >> d >> e;
  long double t = b / c;
  int p = int(t) % int(d + e);
  if (p >= d) {
    cout << setprecision(12)
         << (b / c) + (d + e - double(p) - (t - int(t))) + ((a - b) / c);
  } else {
    cout << setprecision(12) << (b / c) + ((a - b) / c);
  }
}
