I have a calendar week of a given year, like so:

perl -E "use POSIX qw(strftime); say strftime('%Y-%V', localtime)"

How do I generate a unix timestamp for this calendar week? (for example a timestamp for the start of said week).

My use case is that I need to group different timestamps (YYYY-MM-DD) into calendard weeks, but then need a unix timestamps of those weeks to proceed further. I use strftime to convert YYYY-MM-DD into calender weeks, but have difficulties proceeding from there.