Description

Given the coordinates of two endpoints of a line segment A(Xa,Ya) and B(Xb,Yb), calculate the length of segment AB.
The teacher told you the formula: $\sqrt{(X_a-X_b)^2+(Y_a-Y_b)^2}$.

Input Format

The first line contains two real numbers, representing the coordinates of point A.
The second line contains two real numbers, 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 3 decimal places.

Sample

1 1
2 2

1.414