#include <bits/stdc++.h>
using namespace std;
int main(){
  int N, K;
  cin >> N >> K;
  if (K == 1){
    if (N == 1){
      cout << "0" << endl;
    } else if (N == 2){
      cout << "01" << endl;
    } else {
      cout << -1 << endl;
    }
  } else if (K == 2){
    if (N == 2){
      cout << "00" << endl;
    } else if (N == 3){
      cout << "001" << endl;
    } else if (N == 4){
      cout << "0011" << endl;
    } else {
      cout << -1 << endl;
    }
  } else if (K == 3){
    if (N == 3){
      cout << "000" << endl;
    } else if (N == 4){
      cout << "0001" << endl;
    } else if (N == 5){
      cout << "00011" << endl;
    } else if (N == 6){
      cout << "000111" << endl;
    } else if (N == 7){
      cout << "0001011" << endl;
    } else {
      cout << -1 << endl;
    }
  } else {
    string S;
    S += '1';
    for (int i = 0; i < K - 2; i++){
      S += '0';
    }
    S += "1101";
    for (int i = 0; i < K - 2; i++){
      S += '0';
    }
    for (int i = 0; i < K - 2; i++){
      S += '1';
    }
    S += '0';
    string T;
    for (int i = 0; i < N; i++){
      T += S[i % (K * 3)];
    }
    cout << T << endl;
  }
}