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 sys
import math

def str_input():
    S = raw_input()
    if S[len(S)-1] == "\r":
        return S[:len(S)-1]
    return S

def float_to_str(num):
    return str("{:.10f}".format(num))

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

dx = x2 - x1
dy = y2 - y1
print float_to_str(math.sqrt(dx*dx + dy*dy))