#include <bits/stdc++.h>
using namespace std;
int a[1000000];
int main() {
  ios::sync_with_stdio(false);
  int n, m, i, t, k;
  cin >> n >> m;
  if (n - 1 <= m && m <= 2 * (n + 1)) {
    if (m == n - 1) {
      a[0] = -1;
      a[m + 1] = -1;
      t = n - 1;
    } else if (m == n) {
      a[m + 1] = -1;
      t = n;
    } else {
      t = n + 1;
    }
    k = m % t;
    if (k == 0 && m != t) {
      k = n + 1;
    }
    if (a[0] == -1) {
      cout << "0";
    }
    for (i = 1; i <= n; i++) {
      if (a[i] != -1) {
        if (k > 0) {
          cout << "110";
        } else {
          cout << "10";
        }
        k--;
      }
    }
    if (a[m + 1] != -1) {
      if (k > 0) {
        cout << "11" << endl;
      } else {
        cout << "1" << endl;
      }
    }
  } else {
    cout << "-1" << endl;
  }
}
