# The floor is not slippery

Algebra Level 3

$\large \left | x^2 - \left \lfloor \frac{x+1} 2\right \rfloor \right | = 4000$

Find the unique solution of $$x$$ satisfying the equation above.

If you think that there isn't a unique solution, submit your answer as -1.

Notations:

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