#include <bits/stdc++.h>
using namespace std;
string filename = "test";
int main() {
  double res = 0.0;
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  int t = d / v;
  int gr = g + r;
  int left = t % gr;
  int vt = v * t;
  if (vt == d) {
    if (left == 0) {
      res += t;
    } else {
      if (left < g) {
        res += t;
      } else {
        res += t;
        res += (gr - left);
      }
    }
  } else {
    double tt = 1.0 * d / v;
    int itt = (int)(tt);
    left = itt % gr;
    if (left == 0) {
      res += tt;
    } else {
      if (left + 1 <= g)
        res += tt;
      else {
        res += tt;
        res += (gr - left - (tt - itt));
      }
    }
  }
  res += 1.0 * (l - d) / v;
  printf("%.10lf\n", res);
  return 0;
}
