sub build {
    my ($f, $l) = @_;

    my $b = reverse $f;
    substr($b, 0, 1, '') if $l;
    return $f . $b;
}

sub palindrate {
    my $num = shift;

    my $is_odd = length($num) % 2;

    my $first = substr( $num, 0, int(length($num)/2 + .5 ) );

    my $one = build( $first, $is_odd );

    $first += $one < $num ? 1 : -1;
    my $two = build( $first, $is_odd );

    return ((abs($one-$num) < abs($two-$num)) ? $one : $two);
}