N:=17;
X:=y^4 + (x^3 + x^2 - x + 2)*y^3 + (x^3 - 3*x + 1)*y^2 - (x^4 + 2*x)*y + x^3 + x^2;
r:=(x^2 + x - y)/(x^2 + x*y + x - y^2 - y);
s:=(x + 1)/(x + y + 1);
E:=[s-r*s+1,r*s-r^2*s,r*s-r^2*s,0,0];
P:=[0,0];