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

x1,y1,x2,y2 = map(float,raw_input().split())
a = math.sqrt((x1-x2)**2+(y1-y2)**2)
print '%f'%a