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)

ary = gets.split.map(&:to_f)
a = (ary[0] - ary[2]).abs
b = (ary[1] - ary[3]).abs
p Math::sqrt(a**2 + b**2)