1. College of Modern Service Industry, Hefei College of Finance and Economics, Hefei 230601, China
2. Department of Mathematics, University of the Punjab, Lahore, Pakistan
3. Department of Mathematics and Statistics, the University of Lahore, Lahore, Pakistan
4. Department of Mathematics, Division of Science and Technology, University of Education Lahore, Lahore, Pakistan
5. School of Mathematics and Physics, Anhui Jianzhu University, Hefei 230601, China