-1/2 a^{a0}_{c0} b^{v0,v1}_{a1,a2} c^{a3}_{c1} eta1^{a1}_{a0} gamma1^{a2}_{a3} a+(c0) a+(c1) a-(v1) a-(v0)
+1/4 a^{a0}_{c0} b^{v0,v1}_{a1,a2} c^{a3}_{c1} lambda2^{a1,a2}_{a0,a3} a+(c0) a+(c1) a-(v1) a-(v0)