johngg@shiraz:~/perl/Monks > perl -Mstrict -Mwarnings -E '
my $str = q{BEBEBEHUHUHUJJFAFALL};
my %cnt;
$cnt{ $_ } ++ for unpack q{(a2)*}, $str;
say qq{$_ -> $cnt{ $_ }} for sort keys %cnt;'
BE -> 3
FA -> 2
HU -> 3
JJ -> 1
LL -> 1