#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  if (b > 2 * a + 2 || a > b + 1) cout << -1, exit(0);
  while (a && b) {
    if (a > b)
      cout << 0, a--;
    else if (b > a + 1)
      cout << 110, b -= 2, a--;
    else if (b == a + 1)
      cout << 101, b -= 2, a--;
    else if (a == b)
      cout << 10, a--, b--;
  }
  if (b == 2) cout << 11;
  if (b == 1) cout << 1;
  if (a) cout << 0;
}
