introduction to OJ
http://acdream.info/topic/101
ji suan ji he mo ban
http://wenku.baidu.com/link?url=JNBUwmSX6uWJQXTjs3RmHqThCNydjlXb2f6rSt-SyKC1-KLraL42QCo2-DwVw_zdz-nIKfumlkmLJR1UfHpThyOXToh4xy04aQefK_d3wUS
posted on
