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
p = raw_input().split()
x = math.fabs(float(p[0]) - float(p[2]))
y = math.fabs(float(p[1]) - float(p[3]))
print '%.8f' % math.sqrt(x**2 + y**2)