sub abstract_loop($$$) {
    my ($N, $plevel, $pvals) = @_;
    foreach (@list) {
        push @$pvals, $_;
        arbitrary_N_loops($N, $plevel, $pvals);
        pop @$pvals;
    }
}


sub arbitrary_N_loops($;$$) {
    my ($N, $plevel, $pvals) = @_;

    # Check level
    my $level = (!defined($plevel))? 1: $$plevel + 1;
    
    # Initialization (Called once at the beginning of all loops)
    if (1 == $level) {
        $pvals = [ ];
        $nmatch = $total = 0;
    }

    # Call loop N times
    if ($level <= $N) {
        &abstract_loop($N, \$level, $pvals);
    } else {
        # This block only happens within the innermost loop
        match($pvals) and ++$nmatch;
        ++$total;
    }

    # Finalization (Called once at the end of all loops)
    if (0 == --$level) {
        show_results($N, $nmatch, $total);
    }
}

arbitrary_N_loops(1);
arbitrary_N_loops(2);
arbitrary_N_loops(3);
arbitrary_N_loops(4);
arbitrary_N_loops(5);
arbitrary_N_loops(6);
arbitrary_N_loops(7);
arbitrary_N_loops(8);