how to only get NEGATIVE Keywords?

hello, I want to get all Negative Keywords in an account. We could get all keywords by use *AdGroupCriterionService*, and if the items is *NegativeAdGroupCriterion*, then the keyword is Negative. but, there'r so many keywords, system is hard to do it. so, if I could only get Negative Keywords by

a test post

this is a test post, pls delete me if see it, administrator. -- -- =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~ Also find us on our blog and discussion group: http://adwordsapi.blogspot.com http://groups.google.com/group/adwords-api =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~ You