#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;
	
	vector<string> s = {"01","0011","00010111"};
	
	if(K<=3){
		if(s[K-1].size()>=N){
			cout<<s[K-1].substr(0,N)<<endl;
		}
		else{
			cout<<-1<<endl;
		}
	}
	else{
		string ans(K,'0');
		int x = 2,y = 1;
		while(ans.size()<=N){
			rep(i,x)ans += '1';
			rep(i,y)ans += '0';
			if(x==1)x = 2;
			else x = 1;
			if(y==1)y = 2;
			else y = 1;
		}
		
		cout<<ans.substr(0,N)<<endl;
	}
	
	
	return 0;
}