max value in column of alphanumerics, with blanks

Hi. See attached spreadsheet showing extract from a larger sheet.

I have a column of part numbers with alpha prefixes. The column also has blanks.

I need a formula that reports the maximum numeric suffix. i.e. 104801.

The top cell is my current effort, but this doesn't ignore the blanks so returns an error.

Note, the prefix will always be P-COL-.

Thanks.