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)

class Point
  def initialize(x, y)
    @x = x
    @y = y
  end

  attr_reader :x, :y

  def distance(p)
    (((@x - p.x) ** 2.0 + (@y - p.y) ** 2.0) ** 0.5)
  end
end

a,b,c,d=gets.split.map &:to_f
p1=Point.new(a,b)
p2=Point.new(c,d)
puts p1.distance(p2)