Lex Min Binary String

You have a binary string $S$ of length $N$. In one operation, you can: - Choose an index $i \ (1 \le i \lt N)$ such that $S_i \ne S_{i + 1}$; - Delete both $S_i$ and $S_{i + 1}$ from the string. Find the **lexicographically minimal** string that can be formed using any (possibly zero) number of operations. In case it is the null string, output `EMPTY` instead. A string $X$ is lexicographical