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:
data = map(float, raw_input().split())
x1 = data[0]
y1 = data[1]
x2 = data[2]
y2 = data[3]

distance = ((x1 - x2)**2 + (y1 - y2)**2)**0.5
print("{:.8f}".format(distance))