Ukrainian Mathematical Olympiad

Positive integers $A$ and $B$ have the following decimal forms: $A=\overline{abcabc}$ and $B=\overline{d00d}$, where $a,b,c,d$ are decimal digits, $a\ne 0,d\ne 0$. Find all possible values of $a,b,c,d$ such that $A+B$ is a full square.