#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  long long tt = d / v;
  double tc;
  if ((tt % (g + r)) >= g) {
    tc = (double)d / (double)v;
    tt += ((g + r) - (tt % (g + r)));
    tc = tt;
    tc += ((double)l - (double)d) / (double)v;
  } else {
    tc = (double)l / (double)v;
  }
  cout << fixed << setprecision(10) << tc << "\n";
  return 0;
}
