#include <bits/stdc++.h>
int main() {
  double l, d, v, g, r;
  scanf("%lf%lf%lf%lf%lf", &l, &d, &v, &g, &r);
  double t = d / v;
  if (d / v >= g + floor((d / v) / (g + r)) * (g + r) - 1e-9)
    t = (1.0 + floor((d / v) / (g + r))) * (g + r);
  printf("%.9lf\n", (l - d) / v + t);
}
