source_code: import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  public class D5 implements Runnable {
  
  	final double eps = 1e-9;
  
  	private void Solution() throws IOException {
  		double a = nextDouble(), v = nextDouble();
  		double l = nextDouble(), d = nextDouble(), w = nextDouble();
  		double t = 0;
  		if (w + eps > v) {
  			double s = v * v / (2 * a);
  			if (s + eps > l)
  				t = Math.sqrt(2 * l / a);
  			else {
  				double ta = v / a;
  				double sa = a * ta * ta / 2;
  				t = ta + (l - sa) / v;
  			}
  		} else {
  			double sv = v * v / (2 * a);
  			double sw = w * w / (2 * a);
  			if (sw + eps > d) {
  				if (sv + eps > l)
  					t = Math.sqrt(2 * l / a);
  				else {
  					double ta = v / a;
  					double sa = a * ta * ta / 2;
  					t = ta + (l - sa) / v;
  				}
  			} else {
  				double sd = (w * w - v * v) / (-2 * a);
  				if (sv + sd < eps + d)
  					t = v / a + (d - sv - sd) / v + (v - w) / a;
  				else {
  					double f = Math.sqrt(d * a + w * w / 2);
  					t = f / a + (f - w) / a;
  				}
  				if (sd + eps > l - d) {
  					double lv = Math.sqrt((l - d) * 2 * a + w * w);
  					t += (lv - w) / a;
  				} else {
  					t += (v - w) / a + (l - d - sd) / v;
  				}
  			}
  		}
  		out.printf("%.12f", t);
  	}
  
  	public static void main(String[] args) {
  		new D5().run();
  	}
  
  	BufferedReader in;
  	PrintWriter out;
  	StringTokenizer tokenizer;
  
  	public void run() {
  		try {
  			in = new BufferedReader(new InputStreamReader(System.in));
  			out = new PrintWriter(System.out);
  			Solution();
  			out.close();
  		} catch (Exception e) {
  			e.printStackTrace();
  			System.exit(0);
  		}
  	}
  
  	void print(Object... obj) {
  		for (int i = 0; i < obj.length; i++) {
  			if (i != 0)
  				out.print(" ");
  			out.print(obj[i]);
  		}
  	}
  
  	void println(Object... obj) {
  		print(obj);
  		print("\n");
  	}
  
  	int nextInt() throws IOException {
  		return Integer.parseInt(next());
  	}
  
  	long nextLong() throws NumberFormatException, IOException {
  		return Long.parseLong(next());
  	}
  
  	double nextDouble() throws NumberFormatException, IOException {
  		return Double.parseDouble(next());
  	}
  
  	String nextLine() throws IOException {
  		return in.readLine();
  	}
  
  	String next() throws IOException {
  		while (tokenizer == null || !tokenizer.hasMoreTokens())
  			tokenizer = new StringTokenizer(nextLine());
  		return tokenizer.nextToken();
  	}
  }
  