#include <bits/stdc++.h>
using namespace std;
double a, v, l, d, w;
double t1, t2, t3, s1, s2, s3, ans, rv;
int main() {
  scanf("%lf %lf %lf %lf %lf", &a, &v, &l, &d, &w);
  t1 = w / a, t2 = v / a, t3 = (v - w) / a;
  s1 = t1 * w / 2, s2 = t2 * v / 2, s3 = (v + w) * t3 / 2;
  if (v <= w || s1 >= d) {
    if (s2 > l)
      ans = sqrt(l * 2 / a);
    else {
      ans += t2;
      ans += (l - s2) / v;
    }
    printf("%.8lf\n", ans);
    return 0;
  }
  if (s2 + s3 <= d) {
    ans += (t2 + t3);
    ans += (d - s2 - s3) / v;
  } else {
    rv = sqrt((d - s1) * a + w * w);
    ans += (rv / a + (rv - w) / a);
  }
  if (s3 <= l - d) {
    ans += t3;
    ans += (l - d - s3) / v;
  } else
    ans += (sqrt(w * w - 2 * a * (d - l)) - w) / a;
  printf("%.8lf\n", ans);
  return 0;
}
