#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <stack>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
    //1100
    //11101000 3->8
    //11100
    //yukiko
    int n, k; cin>>n>>k;
    if(k==1){
        if(n==1) cout<<"1"<<endl;
        else if(n==2) cout<<"10"<<endl;
        else cout<<-1<<endl;
        return 0;
    }
    if(k==2){
        string s="1100";
        if(n>4) cout<<-1<<endl;
        else{
            for(int i=0; i<n; i++) cout<<s[i];
            cout<<endl;
        }
        return 0;
    }
    if(k==3){
        string s="11101000";
        if(n>8) cout<<-1<<endl;
        else{
            for(int i=0; i<n; i++) cout<<s[i];
            cout<<endl;
        }
        return 0;
    }
    string ans;
    for(int i=0; i<k; i++) ans+='1';
    string s="001011";
    for(int i=0; i<n-k; i++){
        ans+=s[i%6];
    }
    cout<<ans<<endl;
    return 0;
}