Find the eigenvalues of the matrix $$C=\left[\begin{array}{ccc} 1 &0 &-2\cr 0 &-1 &0\cr 0 &0 &-1 \end{array}\right].$$ The eigenvalues are .
(Enter your answers as a comma separated list. The list you enter should have repeated items if there are eigenvalues with multiplicity greater than one.)