#include <iostream>
#include <vector>
#include<map>
#include<string>
#include<algorithm>
#include<sstream>
using namespace std;


int main() {
	int a,b;
	cin >> a>>b;
	int n=0;
	int count=0;
	bool flag = false;
	bool flag2 = true;
	if (a == -1 || b == 0) {
		while (n != 0||flag2) {
			flag2 = false;
			n = a * n + b;
			count++;
		}
		flag = true;
	}
	if (flag) {
		cout << count;
	}
	else {
		cout << -1;
	}
}