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:
# coding:utf-8
import math
array = map(float,raw_input().split())
x1 = array[0]
y1 = array[1]
x2 = array[2]
y2 = array[3]
answer = math.sqrt(math.pow(x2 - x1,2) + math.pow(y2 - y1,2))
print answer