1College of Mathematics and Information Science, Henan Normal University, Xinxiang City, Henan Province, 453007, China. E-mail: qifeng618@hotmail.com
2Department of Computer, Jiaozuo Teachers College, Jiaozuo City, Henan Province, 454001, China.
*The first author was supported in part by the Science Foundation of Project for Fostering Innovation Talents at Universities of Henan Province, China.