1. College of Mathematics and Statistics, Chongqing Technology and Business University, Chongqing, China;
2. Chongqing Key Laboratory of Social Economy and Applied Statistics, Chongqing, China;
3. School of Mathematical Sciences, Dezhou University, Shandong Dezhou, China;
4. School of Mathematical Sciences, Shandong Normal University, Shandong Jinan, China;
5. College of Mathematics and Statistics, Hechi University, Guangxi Yizhou, China