Refer to the given number and symbol series and answer the question that follows. Counting to be done from left to right only. All numbers are single-digit numbers only. (Left) ? 4 ^ / 6 < 2 7 % $4$ 6 9 # 3 9 @ 4 < > (Right) How many such symbols are there, each of which is immediately preceded by another symbol and also immediately followed by a number?