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] = [float(x) for x in raw_input().split()]
print(math.sqrt((x2 - x1) ** 2.0 + (y2 - y1) ** 2.0))