I will officially announce this as Brainfuck Golf Hole #2 on Monday, January 7th, possibly with minor clarifications and/or revisions.
Following up from computing the primes, we'll stick with basic mathematics but add some input. The second task for Brainfuck Golf is to implement a Reverse Polish notation (RPN) calculator program supporting at least addition, subtraction, multiplication, and integer division of the non-negative integers less than 256. The valid inputs for this task are finite RPN expressions with: 1) the binary postfix operators +, -, *, and / respectively denoting addition, subtraction, multiplication, and integer division; 2) integers consistently represented big-endian in exactly one of binary, octal, decimal, or hexadecimal; 3) adjacent integers separated by whitespace; 4) other adjacent elements optionally separated by whitespace; and 5) no other characters such that: 1) the input begins with an integer; 2) at no point while scanning the string will as many operators have been encountered as integers, except when the number of each is 0; 3) the total number of integers in the expression is exactly one greater than the total number of operators; 4) no input integer, intermediate figure, or result to the expression is less than 0 or greater than 255; and 5) no operation in the expression would result in division by zero. A valid entry for this task must, for one of the permitted number formats (binary, octal, decimal, or hexadecimal) and all valid inputs using that format: 1) correctly print the result of the expression using the same number format, followed by a newline; 2) not print anything else; 3) terminate; and 4) never move the memory pointer left from its starting position. -root
