#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-12;
int main() {
  double a, v, l, d, w;
  scanf("%lf%lf%lf%lf%lf", &a, &v, &l, &d, &w);
  w = min(w, v);
  double res;
  double t1 = v / a, t2 = (v - w) / a;
  double l1 = v / 2 * t1, l2 = (v + w) / 2 * t2;
  double v3 = w;
  if (l1 + l2 < d + EPS) {
    res = (d - l1 - l2) / v + t1 + t2;
  } else {
    double tt = sqrt(d * 2 / a);
    double vv = tt * a;
    if (vv + EPS < w) {
      res = tt;
      v3 = vv;
    } else {
      double v2 = sqrt(d * a + w * w / 2);
      res = v2 / a + (v2 - w) / a;
    }
  }
  double t3 = (v - v3) / a, l3 = (v + v3) / 2 * t3;
  double d2 = l - d;
  if (l3 < d2 + EPS) {
    res += t3 + (d2 - l3) / v;
  } else {
    double b = v3 * 2, c = -d2 * 2;
    res += (-b + sqrt(b * b - 4 * a * c)) / a / 2;
  }
  printf("%.7lf\n", res);
  return 0;
}
