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)

line = gets.chomp.split.map(&:to_f)

p1 = [line[0], line[1]]
p2 = [line[2], line[3]]

x = p2[0] - p1[0]
y = p2[1] - p1[1]

l = ((x * x) + (y * y)) ** 0.5

puts l