#include <bits/stdc++.h>
using namespace std;
bool sortbysec(pair<int, int> a, pair<int, int> b) {
  if (a.second != b.second)
    return a.second > b.second;
  else
    return a.first < b.first;
}
int main() {
  long long d, l, k, v, r, g, m;
  double h, rem, ans, f;
  cin >> l >> d >> v >> g >> r;
  h = d / (v * 1.0);
  if (g > h) {
    cout << setprecision(10) << l / (v * 1.0);
  } else {
    m = h;
    k = (ceil(m)) / (g + r);
    f = (m) - (k * (g + r));
    if (f < g) {
      rem = (l - d) / (v * 1.0);
      ans = (k) * (g + r) + rem;
      cout << setprecision(10) << ans;
    } else {
      rem = (l - d) / (v * 1.0);
      ans = (k + 1) * (g + r) + rem;
      cout << setprecision(10) << ans;
    }
  }
}
