C.cpp

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define loop(i,a,b) for(ll i=a;i<b;i++)
#define testcases ll t;cin>>t;while(t--)
#define pb push_back
#define all(x) x.begin(), x.end()
#define dec(x) greater<x>()

int main()
{

	#ifndef ONLINE_JUDGE
	freopen("C:/Users/91731/Documents/input.txt","r",stdin);
	freopen("C:/Users/91731/Documents/output.txt","w",stdout);
	freopen("C:/Users/91731/Documents/error.txt","w",stderr);
    #endif
	
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

	ll n , m ;
	cin>>n>>m;
	if( m> 2*n+2 || m<n-1 )
	{
		cout<<-1<<endl;
		return 0;
	}

	while( n )
	{
		if( m>=n )cout<<1,m--;
		if( m>=n )cout<<1,m--;
		cout<<0,n--;	
	}
	if(m)cout<<1,m--;
	if(m)cout<<1,m--;
	cout<<endl;

	
}