10-in-9 Killer Sudoku

Rules:

Place the numbers from 0 to 9 exactly once in every row, column, and box. Either one or two numbers may be placed in a cell, but no cell may be left empty. One number is already given, and it does not share its cell with another number.

An area outlined by dashes is called a killer cage. All numbers in a killer cage are different and sum to the number in the top left corner of the killer cage.