#include <bits/stdc++.h>
using namespace std;
const long long MOD9 = 1e9 + 7;
const long long MAX = 1e6 + 10;
const double eps = 0.99;
int t, n, m;
vector<int> a;
int main() {
  cin >> n >> m;
  if (n < (m + 1) / 2 - 1 || n > m + 1)
    cout << -1;
  else {
    if (n >= m) {
      if (n > m) cout << "0";
      for (int i = 0; i < m; i++) cout << "10";
    } else {
      a.resize(2 * n);
      for (int i = 0; i < 2 * n; i++) {
        a[i] = 1;
      }
      m -= n;
      for (int i = 0; m != 0; i += 2) {
        if (a.size() <= i) {
          a.push_back(1);
          m--;
        }
        if (m) {
          a[i]++;
          m--;
        }
      }
      for (int i = 0; i < a.size(); i++) {
        if (i % 2)
          cout << 0;
        else
          for (int j = 0; j < a[i]; j++) cout << 1;
      }
    }
  }
}
