Folding Paper

Chef has a rectangular piece of paper. He puts it on a big board in such a way that two sides of the paper are horizontal and two are vertical, and then he performs a sequence of $N$ operations. You are given a string $S$ with length $N$; for each valid $i$, the $i$-th character of $S$ determines the type of the $i$-th operation: - 'R': Pick up the paper from the right side and fold it onto the l