foreach( @files ) {
  my $outfile = outfile_name( $_ );
  open( CUR, $_ ) or die "open $_: $!\n";
  open( OUT, ">$outfile" ) or die "open $outfile: $!\n";

  print OUT $_, "\n";

  while( <CUR> ) {
    last if $. > 4;     
    print OUT;
  }

  close( OUT );
  close( CUR );
}

sub outfile_name {
  my $base = shift;

  return $base . "_distilled"
}