-1/2 a^{v0,v1}_{c0,a0} b^{v2}_{c1} c^{a1}_{v2} gamma1^{a0}_{a1} a+(c0) a+(c1) a-(v1) a-(v0)
+a^{v0,v2}_{c0,a0} b^{v1}_{c1} c^{a1}_{v2} gamma1^{a0}_{a1} a+(c0) a+(c1) a-(v1) a-(v0)