#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  int a,b;cin>>a>>b;
  ll n=0;
  rep2(i,1,100){
    n=n*a+b;
    if(n==0){
      cout<<i<<endl;
      return 0;
    }
  }
  cout<<-1<<endl;
}