#include <bits/stdc++.h>
using namespace std;
string s;
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  if (n > m + 1 || m > (n + 1) * 2) {
    cout << -1 << endl;
    return 0;
  };
  if (n == m + 1) {
    printf("0");
    for (long long i = 0; i < (long long)m; i++) printf("10");
    printf("\n");
    return 0;
  }
  if (n == m) {
    for (long long i = 0; i < (long long)m; i++) printf("10");
    printf("\n");
    return 0;
  }
  int x = m / (n + 1);
  int y = x * (n + 1);
  int z = m - y;
  for (int i = 0; i < z; i++) {
    for (int j = 0; j < x + 1; j++) printf("1");
    printf("0");
  }
  for (int i = z; i < n; i++) {
    for (int j = 0; j < x; j++) printf("1");
    printf("0");
  }
  for (int j = 0; j < x; j++) printf("1");
  printf("\n");
  return 0;
}
