#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double t1 = 1.0 * d / v;
  double t2 = t1;
  double wt = 0.0;
  while (t2 > (g + r)) t2 -= (g + r);
  if (t2 - g >= 0) wt = (r - (t2 - g));
  double ans = t1 + wt + (l - d) / v;
  printf("%.7lf\n", ans);
  return 0;
}
