Counting Machine

Hello peoples.

Challenge: Create a counting machine. The input is between 1 and 15 random-numbered crates, and the output is a single crate with the number of crates inputed.

Puzzle: Now, turning my solution, RUGIXUF, into a puzzle, can you count out a random number of crates. The puzzle has two inputs and one output.
Right: This output gives you how many crates to count.
Middle: Drop crates in here to count them, regardless of their number.
Left: Any cargo dropped in here will lock the middle input, and calculate the result.

Solution: My first solution, FIDURIP, can solve for all values except F.