On the real line place an object at 1. After every flip of a fair coin move the object to the right by 1 unit if the outcome is head and to the left by 1 unit if the outcome is tail.
Let $N$ be a fixed positive integer.Game ends when the object reaches either $0$ or $N$.
What is the probability of the object reaching at $N$, i.e $P(N)$. Give me some hint..