my $inputText = "word1, word2, #18abcdefgh ,word4";

print "before: $inputText\n";

if ( $inputText =~ /#(\d)/g )
    {
    my $n1 = $1;
    if ( $inputText =~ /(\d{$1})/g )
        {
        my $n2 = $1;
        if ( $inputText =~ /(.{$1})/g )
            {
            print "(1) = $n1\n";
            print "(2) = $n2\n";
            print "(3) = $1\n";
            }
        }
    }

print "after: $inputText\n";