87: Robot
Problem statement The infinite in both directions stripe with width 1 is divided into blocks of size 1 x 1. In one of these blocks the robot is located. It can move from one cell to another (the robot at the figure is marked with square). Its movements are determined by the program, each instruction is given by one of three capital letters: L, R, S. The instruction L says the robot to move one cell to the left, the instruction R - to move one square right, and S - to stay in the same cell.