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

x_1,y_1,x_2,y_2 =map(float,raw_input().split())
print (math.sqrt(math.pow(x_2-x_1,2)+math.pow(y_2-y_1,2)))