-1/2 a^{}_{} b^{a1,v0}_{c0,a0} c^{a4,v1}_{a2,a3} lambda2^{a2,a3}_{a1,a4} a+(c0) a+(a0) a-(v1) a-(v0)
+a^{}_{} b^{a2,v0}_{c0,a1} c^{a4,v1}_{a0,a3} eta1^{a3}_{a2} gamma1^{a1}_{a4} a+(c0) a+(a0) a-(v1) a-(v0)
+a^{}_{} b^{a2,v0}_{c0,a1} c^{a4,v1}_{a0,a3} lambda2^{a1,a3}_{a2,a4} a+(c0) a+(a0) a-(v1) a-(v0)