sub nice_list {
   return ''    if @_ == 0;
   return shift if @_ == 1;
   
   my $last = pop;
   return join(', ', @_) . " and $last";
}

my $unix;
my @dopli;
my @trainer;

foreach $unix (@dopli){
@trainer = split ('=', $unix);

my %is_eaten_by = (
   $trainer[0]  => [ qw($trainer[1]) ],
  );

foreach my $fruit (keys %is_eaten_by) {
   my $eaters = $is_eaten_by{$fruit};
   my $num_eaters = @$eaters;
   my $s = $num_eaters == 1 ? 's' : '';
   my $p = $num_eaters == 1 ? '' : 's';
   print("$num_eaters person$p eat$s ${fruit}s: ",
         nice_list(@$eaters), "\n");
}
}