14. Let \( \mathbf{A} \) and \( \mathbf{B} \) be \( n\times n \) matrices. If there exists a nonsingular matrix \( \mathbf{S} \) such that \( \mathbf{B} = \mathbf{S}^{-1}\mathbf{A}\mathbf{S} \), then they have the same eigenvalues.