The Conjecture of Dixmier for the first Weyl algebra is true

Let $K$ be a field of characteristic zero, let $A_1=K[x][\mathrm{\partial }]$ be the first Weyl algebra. In this paper we prove that the Dixmier conjecture for the first Weyl algebra is true, i.e. each algebra endomorphism of the algebra $A_1$ is an automorphism.