006. Distance
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Find the distance between two 2D points. Remember that the distance formula is

$$$d = \sqrt{(x_{2} - x_{1})^2 + (y_{2}-y_{1})^2}$$$

math.sqrt will calculate the square root of a number. Also, you also have to add the line import math at the top of the program.

Input

The first two lines contain the X and Y coordinates of the first point respectively. The second two lines contain the X and Y coordinates of the second point respectively. Each coordinate will have an integer value between -1000 and 1000, inclusive.

Output

A double N representing the distance between the two points

Examples
Input
1
1
2
2
Output
1.4142135623730951
Input
1
1
1
1
Output
0.0