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:
public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		java.util.Scanner scan = new java.util.Scanner(System.in);

		double x1 = scan.nextDouble();
		double y1 = scan.nextDouble();

		double x2 = scan.nextDouble();
		double y2 = scan.nextDouble();

		double kyoriX2 = (x1 - x2) * (x1 - x2);
		double kyoriY2 = (y1 - y2) * (y1 - y2);

		System.out.println(Math.sqrt(kyoriX2 + kyoriY2));
	}

}