  We describe a deterministic algorithm that computes an approximate root of n
complex polynomial equations in n unknowns in average polynomial time with
respect to the size of the input, in the Blum-Shub-Smale model with square
root. It rests upon a derandomization of an algorithm of Beltr\'an and Pardo
and gives a deterministic affirmative answer to Smale's 17th problem. The main
idea is to make use of the randomness contained in the input itself.
