=SUM((D2&E2=A1:A11&B1:B11)*(D3&E3=A2:A12&B2:B12))
This works for me, yielding the same array and result as previous respondents' formulas. Assumes nList is A2:B11 and sList is D2:E3.
However, its relative simplicity makes me think I'm overlooking something...