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:
from math import *
PI = 3.1415926535898
while True:
    try:
    	k = raw_input()
    	if len(k) > 0:
	    	a, b, x, y = map(float, k.strip().split(' '))
	    	print pow((a-x)*(a-x)+(b-y)*(b-y), 0.5)
    except EOFError:
        break