#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  if (2 * n < m - 2) {
    cout << -1;
  } else if (n > m + 1 && n + 1 > m) {
    cout << -1;
  } else {
    while (n > m) {
      cout << 0;
      n -= 1;
      if (n == m) break;
    }
    while (n < m) {
      if (m != 0) {
        cout << 1;
        m -= 1;
      }
      if (m != 0) {
        cout << 1;
        m -= 1;
      }
      if (n != 0) {
        cout << 0;
        n -= 1;
      }
    }
    while (n || m) {
      if (m != 0) {
        cout << 1;
        m -= 1;
      }
      if (n != 0) {
        cout << 0;
        n -= 1;
      }
    }
  }
}
