A for loop works on a list. The inner for loop iterates on the sorted keys of the hash %counted, what we could do is specify a subscript for that list. First, a simple example:

use strict;

my @array = (0..999);

# retrieve only the first 10 elements:
my @top_ten = @array[0..9];

print "$_\n" for @top_ten;
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# ... original code
for ((sort { $counted{$b} <=> $counted{$a} } keys %counted)[0..2]) {
   # ... etc.
}
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# pick one:
my $max = 2; # use [0..$max]
my $max = 3; # use [1..$max] or [0..$max-1]
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jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)