The Knight's Journey

In chess, a knight moves two squares in one direction and one square perpendicular to it: two squares horizontally and one vertically, or one square horizontally and two vertically. On an infinitely large chessboard, a knight standing at $(0, 0)$ can therefore move in a single step to any of $(1, 2)$, $(-1, 2)$, $(1, -2)$, $(-1, -2)$, $(2, 1)$, $(-2, 1)$, $(2, -1)$, $(-2, -1)$.

Given two integers $x$ and $y$, write a program that computes the minimum number of moves a knight needs to travel from $(0, 0)$ to $(x, y)$ on this infinite board.

The input consists of several test cases. Each test case is a single line containing two integers $x$ and $y$ separated by a space. The absolute value of each does not exceed one billion ($10^9$).

The last line of the input contains END, which marks the end of the input.

For each test case, output on its own line the minimum number of moves the knight needs to go from $(0, 0)$ to $(x, y)$.