while (<DATA>)
{
 next if /^\s+$/;
 my $sites = 0;
 if (/\w{1,12}\s+(\d{1,5})\s+[a-zA-Z]{4}/sm){$sites = $1}
 print "$sites\n";
}

__END__
BC001593 91 NPSL
BC001593 262 NASS
BC001593 293 NAST