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 PYTHON3):

Solution:
ax1, ay1, bx1, by1 = map(float, input().split())
print(((bx1 - ax1) ** 2 + (by1 - ay1) ** 2) ** 0.5)