#include <bits/stdc++.h>
using namespace std;
void sb() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
int main() {
  int n, m;
  cin >> n >> m;
  if (m <= 2 * (n + 1) && m >= n - 1) {
    if (m == n - 1 || m == n) {
      bool flag = true;
      if (m == n) flag = false;
      for (int count = 0; count < n;) {
        if (flag) {
          cout << 0;
          count++;
          flag = !flag;
        } else {
          cout << 1;
          flag = !flag;
        }
      }
      cout << endl;
    } else {
      int twos = 0;
      int ones = 0;
      if ((m + n) / (n + 1) > 1) {
        ones = 2 * (n + 1) - m;
        twos = n + 1 - ones;
      } else {
        ones = m;
        twos = 0;
      }
      int j = 0;
      for (int i = 0; i < twos; i++) {
        cout << "11";
        if (j < n) {
          cout << "0";
          j++;
        }
      }
      for (int i = 0; i < ones; i++) {
        cout << "1";
        if (j < n) {
          cout << "0";
          j++;
        }
      }
    }
  } else
    cout << -1 << endl;
}
