I need to extract the integer value from some log files. The integer value always appears after a substring return code . But it may or may not have additional stuff after this substring. Below are two example entries:

Job with id 0 ended with status COMPLETED, return code 16, in 1 minute 12 seconds 
Job with id 0 COMPLETED with return code 255

So, here I want 16 in the first case, and 255 in the second case.

My initial approach was to use awk - but the column in which the required value occurs is not consistent; so it failed.

How do I achieve this in a reliable manner?