Inverting the Square systems is exponential

In this paper, we prove that the degree of regularity of the family of Square systems, an HFE type of systems, over a prime finite field of odd characteristics $q$ is exactly $q$, and therefore prove that \vskip .1in \begin{itemize} \item inverting Square systems algebraically is exponential, when $q=O(n)$, where $n$ is the number of variables of the system. \end{itemize