#include <bits/stdc++.h>
using namespace std;
const int N = 5e5;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long somme = 0;
  int n, m;
  cin >> n >> m;
  if (n >= (m + 2) || m > 2 * (n + 1)) {
    cout << "-1";
    return 0;
  }
  if (n == (m + 1)) {
    cout << "0";
    for (int i = 0; i < m; ++i) {
      cout << "10";
    }
    return 0;
  }
  if (m >= 2 * n + 1) {
    for (int i = 0; i < n; ++i) {
      cout << "110";
    }
    for (int j = 0; j < m - 2 * n; ++j) cout << "1";
    return 0;
  } else {
    for (int i = 0; i < m - n; ++i) {
      cout << "110";
    }
    for (int jj = 0; jj < (int)(2 * n - m); ++jj) cout << "10";
  }
  return 0;
}
