#include<bits/stdc++.h>
// #include<atcoder/all>

using namespace std;
// using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using P = pair<int,int>;
#define rep(i,n) for(ll i = 0;i < (ll)n;i++)
#define ALL(x) (x).begin(),(x).end()
#define MOD 1000000007



int main(){
  
  int n,k;
  cin >> n >> k;
  if(k < (n+1)/2)cout << -1 << "\n";
  else {
    cout << string(k,'0');
    cout << string(n-k,'1');
    cout << "\n";
  }
  

  return 0;
}