A man sat in a round table of 10 seats by himself and put his backpack in a seat

next to him. In the end, He got drunk and did not remember which seat did he put his bag. He

decides to nd it. But he is so drunk that at each step he moves to one of the two adjacent seats

with equal probability. What is the expected number of attempts (i.e. steps) he would take to

nd his backpack?