#include <bits/stdc++.h>
int main() {
  double l, d, v, g, r;
  double t;
  scanf("%lf %lf %lf %lf %lf", &l, &d, &v, &g, &r);
  t = d / v;
  int i;
  for (i = 1;; i++) {
    if (t < i * (g + r)) break;
  }
  if ((i - 1) * (g + r) + g > t) {
    ;
  } else {
    t = (g + r) * i;
  }
  t += (l - d) / v;
  printf("%.8lf\n", t);
}
