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 PYTHON3):

Solution:
import math

x1,y1,x2,y2= map(float,(input().split()))

D=(x2-x1)**2+(y2-y1)**2
d= math.sqrt(D)
print(d)