sub count-jewels ( Str $j, Str $s --> Int ) {
my %counts_of_all = $s.comb.Bag;
my @jewel_list = $j.comb.unique;
return %counts_of_all ∩ @jewel_list.Bag ?? %counts_of_all{ @jewel_list }.sum !! 0;
}
say count-jewels 'aA' , 'aAAbbbb';
say count-jewels 'z' , 'ZZ';