Assistance with Get-content to parse data from one file to create many files - out-file limited to 20 records per file

Hello,

I've received help on my script to read a large file and using Get-Content and Select-String to create multiple files.  My script works like a charm and looks like this:

$input = ".\Move_ClusterGroup_script.txt"

#Create "A" Hosts move scripts.

gc $input | select-string "HOSTA01" | out-file .\HOSTA01.txt
gc $input | select-string "HOSTA02" | out-file .\HOSTA02.txt
gc $input | select-string "HOSTA03" | out-file .\HOSTA03.txt
gc $input | select-string "HOSTA04" | out-file .\HOSTA04.txt
gc $input | select-string "HOSTA05" | out-file .\HOSTA05.txt


#Create "B" Hosts move scripts.
gc $input | select-string "HOSTB01" | out-file .\HOSTB01.txt
gc $input | select-string "HOSTB02" | out-file .\HOSTB02.txt
gc $input | select-string "HOSTB03" | out-file .\HOSTB03.txt
gc $input | select-string "HOSTB04" | out-file .\HOSTB04.txt
gc $input | select-string "HOSTB05" | out-file .\HOSTB05.txt

I'd like to expand on this script with the following requirement:

I'd like to write out at a maximum 20 records per file.  When 20 are reached a new file will be created until all Select-String variables are satisified.  So this would mean that my out-file would need to change and I would see out-file records like .\HostB01_1.txt, .\HostB01_2.txt, .\HostB01_3.txt...etc or something similar that satisify's the requirement.

Thank you.