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: Wrong Answer)


x1, y1, x2, y2 = gets.split(" ").map(&:to_f)

x = x2 - x1
y = y2 - y1

ans = Math.sqrt(x * x + y * y)

puts ans.to_s.split("").to_a[0..9].join