def init_game(n_rows, n_columns, red_discs, yellow_discs):
    """Init an empty game with some initial moves.

    Game is a 2D grid indexed from top left (0,0) to bottom right.
    """

    game = [[" " for _ in range(n_columns)] for _ in range(n_rows)]

    for x, y in red_discs:
        game[x][y] = "R"
    for x, y in yellow_discs:
        game[x][y] = "Y"

    return game