local $/;	# Slurp
for (<DATA> =~ /(?:CWG)?\d{3,}/g) {
    print "ID: $_\n";
}
__DATA__
123
123456,34567889
12345,CWG123456,1234
"Blah Blah 10-20 m can be taken into consideration 1234556"
123,30,40
http://www.takeithere.com/123456789/fig1,987643,34467889 


##</code><code>##

ID: 123
ID: 123456
ID: 34567889
ID: 12345
ID: CWG123456
ID: 1234
ID: 1234556
ID: 123
ID: 123456789
ID: 987643
ID: 34467889