Problem: Write a program which calculates the distance between two points P1(x1, y1) and P2(x2, y2).



Input

Four real numbers x1, y1, x2 and y2 are given in a line.

Output

Print the distance in real number. The output should not contain an absolute error greater than 10-4.

Example

Input

0 0 1 1


Output

1.41421356

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class Main 
{
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		
		double x1= scanner.nextDouble();
		double y1 = scanner.nextDouble();
		
		double x2 = scanner.nextDouble();
		double y2 = scanner.nextDouble();
		
		double d = Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
		System.out.printf("%1$.8f", d);
	}
}