print get_num('.');

sub get_num{
    my $dir = shift;
    (sort{$b<=>$a}
    map{/(\d+)/, $1}<$dir/foo_*.bar>)[0] + 1;
}

##</code><code>##

sub get_num{
    my $dir = shift;
    my $c = 0;
    /(\d+)/ and $1>$c and $c=$1 while <$dir/foo_*.bar>;
    return $c+1;
}