Advent Warmup: Elvish Cheat Codes

Advent Warmup: Elvish Cheat Codes
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In the run up to advent, the elves are playing on their video game console. Before long, one of the elves manages to discover a cheat mode, by entering a sequence of button presses on the controller.

The sequence involves the buttons 'Up', 'Down', 'Left', 'Right', 'A', 'B', and terminates with a single press of the 'Start' button.

The elves begin to ponder the significance of the sequence they discovered, and decide to draw a chart.

Starting at the origin in an (x,y) grid, the buttons Up, Down, Left, Right are imagined to move a cursor a single step in the corresponding direction through the grid. Buttons A and B place corresponding markers at the current cursor location.

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Example:  Up, A, Right, Right, B, Left, B, Start

Taking Right to be the positive x direction, and Up to be the positive y direction. This sequence will move one step up from the origin (0,0), and place an 'A' marker at location (0,1), then a 'B' marker at location (2,1). The cursor will move one step left and another 'B' marker is placed at location (1,1). Then the cursor halts at location (1,1).

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Example:  Up, Up, Down, Down, Left, Right, Left, Right, B, A, Start

Again, starting from the origin (0,0), this sequence will place both a 'B' and an 'A' marker at (0,0), and the cursor will halt at (0,0).

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The taxicab distance ( https://en.wikipedia.org/wiki/Taxicab_distance ) between two grid locations is defined as the (positive) difference between the two points' x values + the (positive) difference between their y values.

eg, between locations (1,2) and (8,6), the difference between the two x values (1 and 8) is 7, and the difference between the two y values (2 and 6) is 4. Therefore, the taxicab distance is 7 + 4 = 11.

Your input is here: https://pastebin.com/wGmzZHeq

Question 1:

Identify the marker furthest from the origin, as measured by the taxicab distance, and return that distance.


Question 2:

Consider all pairs of *different* markers (where a pair may consist of any 'A' and any 'B' marker). Identify the pair maximally far apart from one another, as measured by the taxicab distance, and return that distance.