#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  while (~scanf("%d%d", &m, &n)) {
    if (m > n + 1 || 2 * m + 2 < n) {
      printf("-1\n");
      continue;
    }
    if (m == n + 1) {
      putchar('0');
      for (int i = 1; i <= n; i++) printf("10");
      putchar('\n');
      continue;
    }
    if (m == n) {
      putchar('0');
      m--;
    }
    int k = (n - 2) / 2;
    int _1 = n - 2 * k;
    int _0 = m - k;
    while (_0 >= _1) {
      k--;
      _0++;
      _1 += 2;
    }
    for (int i = 1; i <= k; i++) printf("110");
    for (_0; _0 > 0; _1--, _0--) printf("10");
    for (_1; _1 > 0; _1--) putchar('1');
    putchar('\n');
  }
  return 0;
}
