#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 10000000000000001


int main(){
	
	int N,K;
	cin>>N>>K;
	
	if((N+1)/2 <= K){
		string ans(N,'1');
		rep(i,K)ans[i] = '0';
		cout<<ans<<endl;
	}
	else{
		string s = "";
		
		int x = (K+1)/2;
		int y = 1;
		if(K%2==0)y++;
		
		while(s.size()<=N){
			if(x<=0)break;
			rep(i,x){
				s += '0';
			}
			x--;
			if(y>(K+1)/2)break;
			rep(i,y){
				s += '1';
			}
			
			y++;
			
		}
		
		if(s.size()<N){
			cout<<-1<<endl;
			return 0;
		}
		cout<<s.substr(0,N)<<endl;
		
		
	}
	
	
	return 0;
}