Interesting Set

The numbers $6$, $10$, and $15$ are not perfect squares, yet their product $900 = 30^2$ is a perfect square.

A set of positive integers whose elements multiply to a perfect square is called an interesting set. For example, ${6, 10, 15}$ and ${25}$ are both interesting sets.

The product of all elements of an interesting set is called its value; by definition this value is always a perfect square.

Given a set $S$, write a program that finds the smallest value among all non-empty subsets of $S$ that are interesting sets.

The input consists of several test cases. Each test case is a single line containing two integers $a$ and $b$ with $1 < a < b \le 4900$. These two numbers describe the set $S = {x \in \mathbb{N} \mid a \le x \le b}$, where $\mathbb{N}$ is the set of natural numbers. Process every test case until the end of input.

For each test case, let $k^2$ be the smallest value among all non-empty subsets of $S$ that are interesting sets, and print $k$ on its own line. If no non-empty subset is an interesting set, print none instead.