Square-Substring-Free Number

For an integer $a$, write $a^2$ in decimal notation. A positive integer $N$ is called a square-substring-free number if none of those decimal strings appears as a substring of the decimal representation of $N$.

In increasing order, these numbers begin as $2, 3, 5, 6, 7, 8, 22, 23, 26, \ldots$.

Given a positive integer $N$, find the smallest square-substring-free number that is at least $N$.

A positive integer $N$ is given.

$1 \le N \le 10^{18}$

Print the smallest square-substring-free number that is at least $N$.