Brainteaser - Lego Bricks on the Stairs

Imagine a staircase with at least \( 4 \) steps. You drop \( 1000 \) lego bricks from the top. For each brick, at each step it reaches, it independently stops on that step with probability \( 0.5 \); otherwise, with probability \( 0.5 \), it passes to the next step. What is the expected number of bricks that stop on the \( 4 \)th step?