#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

int max_pan(string s){
    int ans = 1;
    int n = s.size();
    for(int c = 0; c < n; c++){
        for(int l = 1; c-l >= 0 && c+l < n; l++){
            if(s[c-l] != s[c+l]) break;
            chmax(ans, l*2+1);
        }
        for(int l = 1; c-l >= 0 && c+l-1 < n; l++){
            if(s[c-l] != s[c+l-1]) break;
            chmax(ans, l*2);
        }
    }
    return ans;
}

void solve_small(int n, int k){
    set<int> st;
    for(int i = 0; i < (1<<n); i++){
        string s;
        for(int j = 0; j < n; j++){
            if(i&(1<<j)) s += '1';
            else s += '0';
        }
        // cout << s << ' ' << max_pan(s) << endl;
        if(max_pan(s) == k){
            cout << s << endl;
            return;
        }
    }
    cout << -1 << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n, k; cin >> n >> k;
    // test();
    if(n <= 10){
        solve_small(n, k);
        return 0;
    }
    if(k <= 3){
        cout << -1 << endl;
        return 0;
    }
    string t = "1";
    for(int i = 2; i <= k-1; i++) t += "0";
    t += "1";
    t += "01";
    string ans;
    while(ans.size() < n) ans += t;
    while(ans.size() > n) ans.pop_back();
    cout << ans << endl;
    // cout << max_pan(ans) << endl;
}