How do we find the degree of this equation: $$ \sqrt{\left(x-a_{1}\right)^{2}+\left(y-b_{1}\right)^{2}}+\sqrt{\left(x-a_{2}\right)^{2}+\left(y-b_{2}\right)^{2}}+\sqrt{\left(x-a_{3}\right)^{2}+\left(y-b_{3}\right)^{2}}+\sqrt{\left(x-a_{4}\right)^{2}+\left(y-b_{4}\right)^{2}}=R $$
Where $(a_1,b_1),(a_2,b_2),(a_3,b_3),(a_4,b_4)$ are 4 distinct points in the plane, and $R$ is a constant.