#include<bits/stdc++.h>
using namespace std;

#define N 5005
#define endl '\n'
#define ll long long

struct node
{
	double x;
	string s;
}u;
const ll mod=998244353;
ll n,ans;

string bfs(double a,double b)
{
	unordered_map<double,int>vis;
	queue<node>q;
	q.push({a,""});
	while(q.size())
	{
		u=q.front();
		q.pop();
		if(vis[u.x])continue;
		vis[u.x]=1;
		if(abs(u.x-b)<=0.0001)
		{
			return u.s;
		}
		q.push({u.x*0.5,u.s+"1"});
		q.push({u.x+(1-u.x)*0.5,u.s+"2"});
	}
	return "-1";
}

void solve()
{
	double x,y;
	cin>>x>>y;
	cout<<bfs(x,y);
}

int main()
{
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	int tt=1;
	while(tt--)
	{
		solve();
	}
	return 0;
}