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:
#encoding=utf-8

import sys
import math

printf = sys.stdout.write

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

X = x2 - x1
Y = y2 - y1
printf(str(math.sqrt(X**2 + Y**2)))