#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

int main(){
    int N, K; cin >> N >> K;

    if(K == 1){
        if(N >= 3) cout << "-1\n";
        else{
            string S = "01";
            cout << S.substr(0, N) << '\n';
        }
        return 0;
    }

    if(K == 2){
        if(N >= 5) cout << "-1\n";
        else{
            string S = "0011";
            cout << S.substr(0, N) << '\n';
        }
        return 0;
    }

    if(K == 3){
        if(N >= 9) cout << "-1\n";
        else{
            string S = "00010111";
            cout << S.substr(0, N) << '\n';
        }
        return 0;
    }

    string S = "101100";
    string ans;
    rep(i, K) ans += '0';
    rep(i, N-K) ans += S[i%6];

    cout << ans << '\n';
}