while ($line=<INFILE>) {
chomp $line;
if ($line=~/^COMPND[\s]{3}3/) {
$line=join(' ',split(' ',$line));
chop $line;
$chain=substr($line,length($line)-1,1);
$lastchain=$chain;
print OUTFILE ("$chain\n");
} else {
$lastchain='@';
}
}