Singular Values & the SVD · Easy problem

A matrix has SVD $A = U\Sigma V^{T}$ with $U$, $V$ orthogonal $3\times 3$ matrices and $\Sigma = \operatorname{diag}(8, 5, 1)$. Find the largest value of $\|Ax\|$ over all unit vectors $x \in \mathbb{R}^3$.