my $filename;
my $accession_id;
my $sequence_id = "";
my %accession;
my $seq;

print "Please enter in the filename: ";
chomp($filename = <STDIN>);

print "Please enter in the accession_ID: ";
chomp($accession_id = <STDIN>);


open(FILENAME, $filename) or die "cannot open file: $! ";
while($_ = <FILENAME>){

if($_ =~ />/) {
$seq = $_;
} else {
   $accession{$seq} .= $_;
}
}

foreach my $g (keys %accession) {
 if ($accession{$g} =~ m/$accession_id/i){
print "$g\n $accession{$g}\n";
}
}