Write a subroutine NINES_COMPLEMENT, using either pseudo-code or a flowchart, that takes a single numeric digit character as a parameter and returns its "nine's complement" character (the digit character that, when added to the input digit, sums to 9).

For example, if the subroutine is passed the character '3', it should return the character '6' (since $3+6=9$). If it is passed the character '0', it should return the character '9'.

You must make use of the built-in subroutines INT_TO_CHAR and CHAR_TO_INT in your answer:

• CHAR_TO_INT(character) returns the integer ASCII/Unicode code for a character (e.g., CHAR_TO_INT('0') returns 48, and CHAR_TO_INT('9') returns 57).
• INT_TO_CHAR(integer) returns the character corresponding to that ASCII/Unicode code (e.g., INT_TO_CHAR(50) returns '2').

You can assume that the parameter passed to the subroutine will always be a valid digit character between '0' and '9'.