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', $x1, $y1, $x2, $y2);
$x = abs($x1 - $x2);
$y = abs($y1 - $y2);
echo sqrt(pow($x, 2) + pow($y, 2)), PHP_EOL;