E. Equal
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Aqua and Hiyori love equal numbers.

Aqua loves two integers $$$x$$$ and $$$y$$$, and she wants to perform some operations to make $$$x$$$ and $$$y$$$ equal. In one step, Aqua can do one of the following operations:

1. $$$x\leftarrow x+1$$$.

2. $$$y\leftarrow y+2$$$.

Now, Hiyori sets a problem to Aqua: What is the minimum number of steps required to make $$$x$$$ and $$$y$$$ equal?

But Aqua is stupid, could you help her?

Input

The first and only line contains two integers $$$x\ (0\leq x\leq 10^9)$$$ and $$$y\ (0\leq y\leq 10^9)$$$.

Output

Output a single integer — the minimum number of operations required to make $$$x$$$ and $$$y$$$ equal.

Examples
Input
5 10
Output
5
Input
9 3
Output
3