#include <bits/stdc++.h>
using namespace std;
int num[2000005];
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  int ini = 0;
  while (m > n) {
    m--;
    num[ini++] = 1;
    if (m < 0) {
      printf("-1\n");
      return 0;
    }
    if (m == n) break;
    m--;
    num[ini++] = 1;
    if (n == m) break;
    num[ini++] = 0;
    n--;
    if (n < 0 || m < 0) {
      printf("-1\n");
      return 0;
    }
  }
  if (n == m + 1) {
    num[ini++] = 0;
    n--;
  } else if (n > m + 1) {
    printf("-1\n");
    return 0;
  }
  int ult = num[ini - 1];
  while (m > 0 || n > 0) {
    if (ult == 1) {
      ult = 0;
      num[ini++] = 0;
      n--;
    } else {
      ult = 1;
      num[ini++] = 1;
      m--;
    }
  }
  for (int i = 0; i < ini; i++) printf("%d", num[i]);
  printf("\n");
  return 0;
}
