#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=998244353;
#define pai 3.141592653589793238462643383279


  


int main(){
  int n, k; cin >> n>> k;
  if(k<=3){
    if(n>2*k){
      cout << -1 << endl; return 0;
    }
    int ans[2*k] = {};
    for(int i=k; i<2*k; i++){
      ans[i] = 1;
    }
    rep(i, n){
      cout << ans[i];
    }
    cout << endl;
    return 0;
  }
  int ans[k+2] = {};
  rep(i, k+2){
    if(i!=0 && i!=k-1 && i!=k) ans[i] = 1;
  }
  rep(i, n/(k+2)){
    rep(j, k+2){
      cout << ans[j];
    }
  }
  rep(i, n%(k+2)){
    cout << ans[i];
  }
}