MarkErovani cubes

Vitek has a set of cubes featuring both lowercase and uppercase English letters. Recently, his mother gave him a set of cubes with digits, so Vitek quickly learned to count up to $10$. However, his father unwittingly gave him a set of colorful markers, after which Vitek began experimenting with the digit cubes: he would color over a number and draw the next higher digit in its place. Since he knew that the digit $10$ does not exist, he would always write $0$ instead of $10$.

Note that sometimes Vitek's mother called him for a meal, and he did not have time to finish his work and write the next digit—in this case, the cube remained blank forever, and such cubes are denoted by the space character.

Your task is to help Vitek by writing a program that performs the next marking of the cubes according to these rules. Since you are not at home but at an olympiad, your mother will not call you for a meal, and you must finish the task.