import java.util.*;

public class Main {
    public static void main(String args[]) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt(); 
        int n = 0;
        Set<Integer> seen = new HashSet<>();
        while(!seen.contains(n)) {
        	seen.add(n);
        	n = a *  n + b;
        }

        System.out.println(n == 0 ? seen.size() : -1);	
    }
}