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
  list($x1, $y1, $x2, $y2) = explode(" ", trim(fgets(STDIN)));
  $a = pow(($x2 - $x1), 2);
  $b = pow(($y2 - $y1), 2);
  print sqrt($a + $b);
?>