Consider the 3×33 \times 33×3 permutation matrix P=(010001100)P = \begin{pmatrix} 0 & 1 & 0 \\ 0 & 0 & 1 \\ 1 & 0 & 0 \end{pmatrix}P=001100010. What is the real eigenvalue of PPP?
000
111
−1-1−1
222