Problem:
Score: 300 points

Problem Statement

Consider an analog clock whose hour and minute hands are A and B centimeters long, respectively.

An endpoint of the hour hand and an endpoint of the minute hand are fixed at the same point, around which each hand rotates clockwise at constant angular velocity. It takes the hour and minute hands 12 hours and 1 hour to make one full rotation, respectively.

At 0 o'clock, the two hands overlap each other. H hours and M minutes later, what is the distance in centimeters between the unfixed endpoints of the hands?

Constraints

All values in input are integers.

1 \leq A, B \leq 1000

0 \leq H \leq 11

0 \leq M \leq 59

Input

Input is given from Standard Input in the following format:

A B H M

Output

Print the answer without units. Your output will be accepted when its absolute or relative error from the correct value is at most 10^{-9}.

Sample Input 1

3 4 9 0

Sample Output 1

5.00000000000000000000

The two hands will be in the positions shown in the figure below, so the answer is 5 centimeters.

Sample Input 2

3 4 10 40

Sample Output 2

4.56425719433005567605

The two hands will be in the positions shown in the figure below. Note that each hand always rotates at constant angular velocity.

Solution in Java (OpenJDK 11.0.6) (judge verdict: Accepted)

//--- pC ---//
import java.util.*;
import java.lang.*;
import java.io.*;
public class Main {
	public static void main (String[] args) throws java.lang.Exception {
		new Solution();
	}
}
class Solution {
	Reader reader;
	PrintWriter out;
	public Solution() {
		reader = new Reader();
		out = new PrintWriter(System.out);
		while (reader.hasNext()) {
			run_case();
		}
		out.flush();
	}

	private void run_case() {
		double a = Double.parseDouble(reader.ns());
		double b = Double.parseDouble(reader.ns());
		double h = Double.parseDouble(reader.ns());
		double m = Double.parseDouble(reader.ns());

		double angle = calcAngle(h, m);
		double c = a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(angle));

		c = Math.sqrt(c);
		
		out.println(c);

		return;
	}

	private double calcAngle(double h, double m) {
        double hour_angle = (0.5 * (h*60 + m));
        double minute_angle = (6*m);
        double angle = Math.abs(hour_angle - minute_angle);
        angle = Math.min(360-angle, angle);
        return angle;
    }
}


class Reader {
	BufferedReader br;
	StringTokenizer st;
	public Reader(){
		try {
			br = new BufferedReader(new InputStreamReader(System.in));
			st = new StringTokenizer(br.readLine());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public String next() {
		if (st.hasMoreTokens()) return st.nextToken();
		try {
			st = new StringTokenizer(br.readLine());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return st.nextToken();
	}
	public boolean hasNext() {
		try {
			if (!st.hasMoreTokens() && !br.ready()) return false;
			else return true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}
	public int ni() {return Integer.parseInt(this.next());}
	public long nl() {return Long.parseLong(this.next());}
	public String ns() {return this.next();}
}