1. Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Pakistan
2. Mathematics Department, Faculty of Science, Taibah University, Al-Madinah Al-Munawarah, Saudi Arabia
3. Department of Computer Science, University of the Punjab, Lahore, Pakistan
4. Department of Mathematics, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia