N, K = gets.split.map(&:to_i)

def f
  0.upto(2 ** N - 1) do |mask|
    str = mask.to_s(2).rjust(N, '0')
    ok = true
    found = false

    N.downto(K) do |k|
      0.upto(N - k) do |i|
        s = str[i...i + k]

        if s == s.reverse
          if k > K
            ok = false
          else
            found = true
          end
        end
      end
    end

    return str if ok && found
  end

  false
end

if N <= 9
  if res = f
    puts res
  else
    puts -1
  end
elsif K <= 3
  puts -1
else
  tmp = '010011'
  len = 6
  str = ('1' * K) + tmp * Rational(N, len).ceil
  puts str[0...N]
end