use strict;
my $num = shift;
if ($num) {
    if ($num % 2) {
        print "$num is calling system...\n";
        system("perl test.pl " . ($num - 1));
        print "$num is finished calling system.\n";
    } else {
        print "$num is calling exec...\n";
        exec("perl test.pl " . ($num - 1));
        print "$num finished calling exec.\n";
    }
}