Among the countries in the group of Heavily Indebted Poor Countries, how many of them are under the lending category of the International Development Associations?
group of Heavily Indebted Poor Countries is OtherGroups = 'HIPC'; International Development Associations refers to lendingcategory = 'IDA'
SELECT COUNT(CountryCode) FROM Country WHERE LendingCategory = 'IDA' AND OtherGroups = 'HIPC'