编写一个程序：有n个人围成一圈，顺序排号。从第一个人开始报数（从1到3报数），凡报到3的人退出圈子，问最后留下的是原来第几号的那位。(The preparation of a program: n personal circle, order arranging. Started from the first report (from 1 to 3 report), who reported 3 people out of the circle, leaving the last question is the original number.)