Instructions

Given a string of digits, output all the contiguous substrings of length n in that string in the order that they appear.

For example, the string "49142" has the following 3-digit series:

And the following 4-digit series:

And if you ask for a 6-digit series from a 5-digit string, you deserve whatever you get.

Note that these series are only required to occupy adjacent positions in the input; the digits need not be numerically consecutive.

Output a null-terminated string, using a comma and a space as separators.

An example output would be "491, 914, 142"

If the input is invalid, output an empty string.

Register	Usage	Type	Description
`$a0`	input	address	null-terminated series string
`$a1`	input	integer	slice length
`$a2`	input/output	address	null-terminated output string
`$t0-9`	temporary	any	used for temporary storage