Problem: 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.

Example

Input

0 0 1 1


Output

1.41421356

Solution (in PYTHON):

Solution:

import math

z = raw_input()
x1, y1, x2, y2 = z.split()
x1 = float(x1)
x2 = float(x2)
y1 = float(y1)
y2 = float(y2)

d = math.sqrt((x2 - x1) * (x2-x1) + (y2 - y1) * (y2 - y1))

print ("%lf" %(d))