Fox.java

import java.util.Scanner;
//http://codeforces.com/problemset/problem/371/B


public class Fox {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[][] facts = new int[2][4];
		facts[0][3] = sc.nextInt();
		facts[1][3] = sc.nextInt();
		int[] factors = { 2, 3, 5 };
		for (int j = 0; j < facts.length; j++)
			for (int i = 0; i < factors.length; i++)
				while (facts[j][3] % factors[i] == 0) {
					facts[j][3]/=factors[i];
					facts[j][i]++;
				}
				
		if(facts[0][3] != facts[1][3])
			System.out.println(-1);
		else{
			int ans = 0;
			for(int i = 0; i < 3; i++)
				ans+= Math.abs(facts[0][i]-facts[1][i]);
			System.out.println(ans);
		}
	}
}