@a = qw/5 7 2 5 1 3/;
undef @{$h{a}}{5, 4, 3};
undef @{$h{b}}{7, 9, 6};
undef @{$h{c}}{0, 2, 1};

for $x (@a){
		exists $h{$_}{$x} and print "$x pool $_\n" for keys %h;
}