DK-GEORGMOHR 2017 Problem 4

Let $A, B, C$ and $D$ denote the digits in a four-digit number $n = ABCD$ . Determine the least $n$ greater than $2017$ satisfying that there exists an integer $x$ such that $$x =\sqrt{A +\sqrt{B +\sqrt{C +\sqrt{D + x}}}}.$$