Write SQL query to solve given problem: What is the difference between the number of returned items and not returned items with the full price of under 16947.7?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT SUM(IIF(l_returnflag = 'A', 1, 0)) - SUM(IIF(l_returnflag = 'N', 1, 0)) AS diff FROM lineitem WHERE l_extendedprice < 16947.7