// The "Q1" class.
import java.awt.*;
import java.io.*;
public class Q1_edited
{
    public static void main (String[] args) throws IOException
    {

	BufferedReader fin = new BufferedReader (new FileReader ("DATA1.txt"));
	PrintWriter fout = new PrintWriter (new FileWriter ("OUT1.txt"));
	for (int a = 0 ; a < 5 ; a++)
	{
	    String s[] = fin.readLine ().split (" ");
	    int x1 = Integer.parseInt (s [0]);
	    int y1 = Integer.parseInt (s [1]);
	    int x2 = Integer.parseInt (s [2]);
	    int y2 = Integer.parseInt (s [3]);

	    double A= Math.pow ((Math.pow(y1,2) + Math.pow (x1,2)),1/2);
	    
	    double B= Math.pow ((Math.pow(y2,2) + Math.pow (x2,2)),1/2);
	    
	    double C=Math.pow ((Math.pow((y2-y1),2) + Math.pow ((x2-x1),2)),1/2);
	    
	    double T=Math.toDegrees (Math.acos ( (C*C-A*A-B*B)/(-2*A*B)));
	   
	    if (y2 <= y1)
	    {
		T = 360 - T;
	    }
	    fout.println (T, 0, 1);
	}
	fout.close ();

	// Place your program here.  'c' is the output console
    } // main method
} // Q1 class