七个:
F(a)=-1,F(b)=-1,F(c)=0;
F(a)=-1,F(b)=0,F(c)=-1;
F(a)=0,F(b)=0,F(c)=0;
F(a)=0,F(b)=-1,F(c)=1;
F(a)=0,F(b)=1,F(c)=-1;
F(a)=1,F(b)=0,F(c)=1;
F(a)=1,F(b)=1,F(c)=0
七个:
F(a)=-1,F(b)=-1,F(c)=0;
F(a)=-1,F(b)=0,F(c)=-1;
F(a)=0,F(b)=0,F(c)=0;
F(a)=0,F(b)=-1,F(c)=1;
F(a)=0,F(b)=1,F(c)=-1;
F(a)=1,F(b)=0,F(c)=1;
F(a)=1,F(b)=1,F(c)=0