Solution
= Solution
Integrating by parts gives
$$
\widetilde a=-a,
\qquad
\widetilde b=-(b+c),
$$
because the $b$ and $c$ terms differ only by a total derivative. Hence
$$
\mathcal L\simeq
\widetilde a V_\nu\Box V^\nu
+\widetilde b V^\nu\partial_\nu\partial_\mu V^\mu
+m^2V^\mu V_\mu.
$$