open(INPUT,'<',$filename) or die $!;

##</code><code>##

open(BSC,'>','BSC') or die $!;

##</code><code>##

for my $searchline(<INPUT>) {
    if( $searchline =~ /20041204/ ) {
        if( $searchline =~ /^BSC/) {
            print BSC $searchline;
        }
    }
}