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 = raw_input().split()

tei  = float(x2) - float(x1)
taka = float(y2) - float(y1)

if tei == taka:
    st = math.sqrt(2)
    answ = st * tei
    print answ
if tei != taka:
    answ = (tei*tei) + (taka*taka)
    print math.sqrt(answ)