clear;

//We just do l=3, since t=0 there

q:=13;
Fq:=GF(q);
a:=2; b:=1;
E:=EllipticCurve([Fq|2,1]);
Poly<x,y>:=PolynomialRing(Fq,2);
Exy:=y^2-(x^3+a*x+b);

l:=3;
psi3:=Evaluate(DivisionPolynomial(E,3),x);
I3:=Ideal([Exy,psi3]);
R3:=quo<Poly|I3>;

R3!(x^(q^2)); 
R3!x; 
