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 Ruby (judge verdict: Accepted)

#encoding: utf-8                                                                       

require 'complex'

x1, y1, x2, y2 = gets.chomp.split(/\s/).collect { |x| x.to_f }

p1 = Complex(x1, y1)
p2 = Complex(x2, y2)

puts ("%6f" % (p2 - p1).abs)