#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("YES");}else{puts("NO");}
#define MAX_N 200005

int main() {
    int n, k;
    cin >> n >> k;

    if(k*2>=n){
        rep(i,k) cout << '0';
        rep(i,n-k) cout << '1';
        cout << endl;
        return 0;
    }

    if(k == 3){
        cout << -1 << endl;
        return 0;
    }

    string s;
    rep(i,k-2) s += '0';
    rep(i,k-2) s += '1';
    s += '0';
    s += '1';

    string ans;
    int m = s.size();
    rep(i,n) ans += s[i%m];

    cout << ans << endl;
    return 0;
}