use strict;

my @Group1 = qw( H0 K0 PA PB PC PD PE PF PG PH );
my @Group2 = qw( PX PY PZ P1 P2 P3 P4 P5 P6 P7 );

my @G1_out;
my @G2_out;

while (my $input = <DATA>) {
    chomp ($input);
    my $prefix = substr($input,0,2);

    # NB: grep is slow in this case. evil. beware.
    push (@G1_out, $input) if grep($_ eq $prefix, @Group1);
    push (@G2_out, $input) if grep($_ eq $prefix, @Group2);
}

print "G1\n";
print "$_\n" foreach @G1_out;
print "\nG2\n";
print "$_\n" foreach @G2_out;

__DATA__
A1 # invalid
K0 # valid G1
B4 # invalid
PY # valid G2

##</code><code>##

G1
K0 # valid G1

G2
PY # valid G2