sub execution {
    my ($quantity, $claws) = @_;

    throw Exception('quantity and number of claws must be matched!\n')
        if( $quantity != scalar(@$claws) );

    my @list;
    push @list, 1 for( 1 .. $quantity );

    my $exec = [];
    my $i = 0;
    while( $i < $quantity ) {
        $exec->[$i] = [];
        for( 0 .. ($quantity-1) ) {
            if( ( $_ < $i) and ( $_ >= ( $i - $claws->[$i]) ) ) {
                $list[$_] &= 0;
            }
            else {
                $list[$_] &= 1;
            }
        }
        $i++;
    }
    my $counter = 0;
    $counter += $_ for( @list );

    return $counter;
}