Its solution with a=1,2
[[[n,add3],[[v,a],[v,b]],:-,[[[n,tail],[[v,a],[v,b]]]]],[[n,add0],[[v,a],[v,b]],:-,[[[n,add3],[[v,a],[v,c]]],[[n,add3],[[v,c],[v,d]]],[[n,=],[[v,d],[v,b]]]]]]