Problem:
Distance

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.

Sample Input

0 0 1 1

Sample Output

1.41421356

Solution in PHP (judge verdict: Accepted)

<?php

fscanf(STDIN, "%f %f %f %f", $x_1, $y_1, $x_2, $y_2);
$x_diff = abs($x_2 - $x_1);
$y_diff = abs($y_2 - $y_1);

$x_diff = $x_diff ** 2;
$y_diff = $y_diff ** 2;

echo sqrt($x_diff+$y_diff)."\n";