Crypto Japanese Cave with Three Extraterrestrials

Rules:

Shade some cells in the grid such that all unshaded cells are orthogonally connected, and all orthogonally connected groups of shaded cells touch the perimeter of the grid. Then, enter numbers from 1 to 9 in every unshaded cell such that no number repeats in a row or column. Numbers must not be placed in shaded cells.

Clues outside the grid indicate the sums of connected groups of numbers in the respective row or column, in order, where shaded cells serve as delimiters between groups.

The clues have been written by three extraterrestrials, each of which is familiar with only one number base, which might not be our usual 10. However, it is unknown which extraterrestrial wrote which clue. A letter can replace any number from 0 to N-1, where N is the base of the clue, and no two letters replace the same number. No clue may have a leading zero.