**random walk**. He starts at 0, and moves 1 unit to the left or right, with equal probability. On the next step, he moves 2 units to the left or right, again with equal probability. For subsequent turns he follows the pattern 1, 2, 1, 2 etc.

His keys, in truth, were right under his nose at point 0. Assuming that he'll spot them the next time he sees them, what is the probability that Jorge will eventually return to 0?

__Note__: For purposes of the problem, assume that Jorge is not looking while he is merely passing through a point. For example, he will not look for his keys while he passes through 0.