Description

Given the coordinates of two endpoints of a line segment A(X~a~, Y~a~) and B(X~b~, Y~b~), calculate the length of segment AB, rounded to three decimal places.

Input Format

The first line contains two real numbers X~a~ and Y~a~, representing the coordinates of point A.
The second line contains two real numbers X~b~ and Y~b~, representing the coordinates of point B.
All real numbers in the input have absolute values not exceeding 10000.

Output Format

A real number representing the length of segment AB, rounded to three decimal places.

1 1
2 2

1.414