#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  if (m < n - 1 || n + 1 < (m + 1) / 2)
    cout << "-1";
  else if (m == n || abs(n - m) == 1) {
    while (m != 0 && n != 0) {
      cout << "01";
      n--;
      m--;
    }
    if (n == 1) cout << "0";
    if (m == 1) cout << "1";
  } else if (2 * n - m > 0) {
    int a = m - n;
    while (a--) {
      cout << "011";
    }
    int b = 2 * n - m;
    while (b--) {
      cout << "01";
    }
  } else {
    while (n--) {
      cout << "110";
      m = m - 2;
    }
    while (m--) cout << "1";
  }
  return 0;
}
