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:
r=map(float,raw_input().split())
x=r[0]-r[2]
y=r[1]-r[3]
if x<0:
        x=x*-1
if y<0:
        y=y*-1
print (x**2+y**2)**0.5