eq(f3(A),1,[f1(A,B,C),loop_cont_f1(C)],[B=0,A>=0]).
eq(f3(A),1,[f1(A,B,C)],[B=1,A>=0]).
eq(f1(A,B,C),1,[f1(A-1,B,C)],[A>=1]).
eq(f1(A,B,A),0,[],[B=1]).