while (<IN>) # Note: using $_ instead
{
    my (@two, @rest);
    chomp;
    @rest = split; # Note that this is the same as (split ' ', $_) .
                   # ' ' is generally a better choice than /\s/ for splitting on
                   # whitespace.  If you need to count multiple spaces as
                   # multiple fields, use /\s/ or / / instead.
    @two = splice @rest, 0, 2;
    print join(' ',@two,undef),join('|',@rest),"\n"; # The undef is to put another space in before @rest
}