#include <bits/stdc++.h>
using namespace std;
int main() {
  long int a, b, p, i = 0, k = 0;
  cin >> a >> b;
  if (b == a - 1) {
    while (i < a + b - 1) {
      cout << "01";
      i = i + 2;
    }
    cout << "0";
  } else if ((b <= (2 * a + 2)) && (a < b + 1)) {
    p = b - a;
    while (i < a + b) {
      if (p > 0) {
        cout << "1";
        p--;
        i++;
      }
      if (k < a) {
        cout << "10";
        i = i + 2;
        k++;
      }
    }
  } else
    cout << "-1";
  return 0;
}
