Department of Computer Science and Engineering, Pohang University of Science and Technology, San 31 Hyo-Ja Dong, Pohang 790-784, Republic of Korea. raghava@imtech.res.in|Department of Computer Science and Engineering, Pohang University of Science and Technology, San 31 Hyo-Ja Dong, Pohang 790-784, Republic of Korea. raghava@imtech.res.in