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
m=[float(i)for i in input().split()]
x=m[2]-m[0]
y=m[3]-m[1]
print(math.sqrt(float(x*x+y*y)))