eq(f0(A,B,C,D),1,[f1(A,B,C,D,E,F,G,H,I),loop_cont_f1(F,G,H,I)],[E=0]).
eq(f0(A,B,C,D),1,[f1(A,B,C,D,E,F,G,H,I)],[E=1]).
eq(f1(A,B,C,D,E,F,G,H,I),1,[f1(A+B,B+C,C+D,D-1,E,F,G,H,I)],[A>=1]).
eq(f1(A,B,C,D,E,F,G,H,I),1,[f1(A-1,B,C,D,E,F,G,H,I)],[A>=1]).
eq(f1(A,B,C,D,E,A,B,C,D),0,[],[E=1]).