use strict;
use warnings;

while (<DATA>)
{
	print "$1\n" if m/GO:(\d+)/
}

__DATA__

dd class="xref">GeneID:947412</dd>
                        
                    
                    <dd class="xref">GenomeReviews:AP009048_GR</dd>
                        
                    
                    <dd class="xref">GenomeReviews:U00096_GR</dd>
                        
                    
                    <dd class="xref"><a href="http://amigo.geneontology.org/cgi-
+bin/amigo/term-details.cgi?term=GO:0005524">GO:0005524</a></dd>
                        
                    
                    <dd class="xref"><a href="http://amigo.geneontology.org/cgi-
+bin/amigo/term-details.cgi?term=GO:0005886">GO:0005886</a></dd>
                        
                    
                    <dd class="xref"><a href="http://amigo.geneontology.org/cgi-
+bin/amigo/term-details.cgi?term=GO:0006810">GO:0006810</a></dd>
                        
                    
                    <dd class="xref"><a href="http://amigo.geneontology.org/cgi-
+bin/amigo/term-details.cgi?term=GO:0016301">GO:0016301</a></dd>
                        
                    
                    <dd class="xref">HOGENOM:P27254</dd>