#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const long long INF = 0x7FFFFFFFFFFFFFFF / 2;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int nn, mm;
  cin >> nn >> mm;
  int n = nn, m = mm;
  int tto = 0, to = 0;
  while (n > 0 && m > 0) {
    if (n >= 1 && m >= 2) {
      tto++;
      n--;
      m--;
      m--;
    } else {
      break;
    }
  }
  while (n > 0 && m > 0) {
    if (n >= 1 && m >= 1) {
      to++;
      n--;
      m--;
    } else {
      break;
    }
  }
  while (m > 0) {
    if (to) {
      to--;
      tto++;
      m--;
    } else {
      break;
    }
  }
  while (n > 0) {
    if (tto) {
      to++;
      to++;
      tto--;
      n--;
    } else {
      break;
    }
  }
  if (n > 1 || m > 2) {
    cout << "-1";
    return 0;
  }
  if (m == 0 && n == 1) {
    cout << "0";
    for (int i = 0; i < to; i++) cout << "10";
    for (int i = 0; i < tto; i++) cout << "110";
  } else if (n == 0 && m <= 2) {
    for (int i = 0; i < to; i++) cout << "10";
    for (int i = 0; i < tto; i++) cout << "110";
    for (int i = 0; i < m; i++) cout << "1";
  }
  return 0;
}
