Hello Perl Monks!

I'm struggling with multi line matches, hoping someone can offer advice.

I have text files with data that looks like this:
123,-->456,
456,-->234,
234,-->789,
789,-->123,

I am trying to print the first three digits of the each line followed by the second three digits of the following line to my OUTFILE on a single line. So the output for the four lines above would be:
123,-->234,
456,-->789,
234,-->123,

From what I've been reading I need to use the /s or /m modifier to match a newline. I've been trying to use /s to have "." match a newline. My code looks like this:

@files=glob"SBNUM_*.txt";


open OUTFILE, ">v2test.txt" or die "Could not create outfile!";


foreach $ARG(@files){

open INFILE, "<$ARG" or die "CANNOTOPENINFILE";


while (<INFILE>)
 

{

    if (m/^(\d\d\d),-->(\d\d\d),.(\d\d\d),-->(\d\d\d),/s) 
    
    {

    
    print OUTFILE "\n$1,-->$4,";

    }

    
}
}
[download]

I have tried a few variations but so far nothing works for me. Any advice or suggestions are greatly appreciated!

TJ