use strict;
use warnings;

while (<DATA>){
  my $input = $_;
  if ( ## are you sure the format is correct?
       $input =~ 
       m/^(\w{3}) ## match 3 alphanumerics at the start
          [^\d]*  ## non digits in the middle
          (\d+)   ## capture all the digits before
          \.      ## an actual dot 
        /x 
  ){
    my $site_code = $1;
    my @rs = split '', $2; ## split the digits up into an array
    print "Input : $input\n\$site_code : \'$site_code\'\n\@rs :\n\t", (join "\n\t", @rs), "\n";
  }
  else{
    ## ... process alternately?
    print "input \'$input\' cannot be processed.\n";
  }
}


__DATA__
uk1sxve01205.gfjgjf5.fdhd5
usasxve513.gfdhf4.hgfd4
how_did_this_get_here?