Given two numbers \(A\) and \(B\), find the smallest prime number that divides both of them or state that such number does not exist.

Input

First and only line of input contains two integers \(A\) and \(B\).

Output

Print the smallest common prime divisor of \(A\) and \(B\) or \(-1\) if it does not exist.

Constraints

\(1 \le A,B \le 10^{15}\)