function A = build_A(X,Y,n)
    [row_num, ~] = size(X);
    X = reshape(X, [row_num^2,1]);
    Y = reshape(Y,[row_num^2, 1]);
    A = [];
    for i = 0:1:n
        for j = 0:1:(n - i)
            A = [A,(X.^i) .* (Y.^j)];
        end
    end

end