import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


int[] manacher(T)(T a) {
  const n = cast(int)(a.length);
  auto r = new int[n * 2];
  for (int i = 0, j = 0, k; i < n * 2; i += k, j = max(j - k, 0)) {
    for (; 0 <= i - j && i + j + 1 < n * 2 && a[(i - j) / 2] == a[(i + j + 1) / 2]; ++j) {}
    r[i] = j;
    for (k = 1; 0 <= i - k && 0 <= j - k && r[i - k] != j - k; ++k) {
      r[i + k] = min(r[i - k], j - k);
    }
  }
  return r;
}

void main() {
  enum lim = 16;
  auto sss = new string[][lim];
  foreach (n; 1 .. lim) {
    sss[n] = new string[n + 1];
    foreach (p; 0 .. 1 << n) {
      string s;
      foreach (i; 0 .. n) {
        s ~= cast(char)('0' + ((p >> i) & 1));
      }
      const k = manacher(s).maxElement;
      if (!sss[n][k]) {
        sss[n][k] = s;
      }
    }
    debug {
      writeln(n, ": ", sss[n]);
      stdout.flush;
    }
  }
  
  try {
    for (; ; ) {
      const N = readInt();
      const K = readInt();
      
      if (N < lim) {
        if (sss[N][K]) {
          writeln(sss[N][K]);
        } else {
          writeln(-1);
        }
      } else {
        if (K >= 4) {
          auto ans = new char[N];
          ans[0 .. K] = '0';
          foreach (i; K .. N) {
            ans[i] = "101100"[(i - K) % $];
          }
          writeln(ans);
          
          debug {
            writeln(manacher(ans).maxElement);
          }
        } else {
          writeln(-1);
        }
      }
    }
  } catch (EOFException e) {
  }
}