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)

MODE = "stdio"
require 'matrix'
line = Array.new

if(defined? MODE)
  line = STDIN.read.split("\n")
else
  tmp = '0 1.5 1 1'.split("\n")
  tmp.each{|s|
    line << s.strip
  }
end


x1,y1,x2,y2 = line[0].split(" ").map(&:to_f)

d =  ((x2-x1)**2 + (y2-y1)**2)**(0.5)

printf("%.10f\n",d)