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:
a,b,c,d=map(float,input().split())

k=c-a
l=d-b

n=(k*k+l*l)**(1/2)

print('{:.8f}'.format(n))