The first line of the standard input gives a single -letter word (1<=N<=100000) composed of the letters L and P, describing the sequence of successive turns made during the maze's traversal.
构造一个n个顶点的多边形,按照它的边缘走,如果右转就是P,左转就是L。输出每个点的顶点
LLLLPPLL
0 0
2 0
2 2
-1 2
-1 -2
1 -2
1 -1
0 -1