N, K = map(int, input().split())

if K == 1:
    if N == 1:
        print(0)
    else:
        print(-1)
elif K > N:
    print(-1)
else:
    required_min = (N + 1) // 2
    if K < required_min:
        print(-1)
    else:
        if K == N:
            print('0' * N)
        else:
            # Construct the palindrome part
            if K % 2 == 0:
                half = K // 2
                first_part = ['0'] + ['1'] * (half - 1)
                first_part = first_part[:half]  # Ensure correct length
                second_part = first_part[::-1]
                palindrome = ''.join(first_part + second_part)
            else:
                m = (K - 1) // 2
                first_part = ['0'] + ['1'] * (m - 1)
                first_part = first_part[:m]  # first m-1 characters?
                middle = ['0']
                second_part = first_part[::-1]
                palindrome = ''.join(first_part + middle + second_part)
            
            # Append remaining characters
            remaining_length = N - K
            if remaining_length > 0:
                # The last character of the palindrome is '0' for even, '1' or '0' for odd
                # We append '1' followed by '0's to break any possible palindromes
                remaining = '1' + '0' * (remaining_length - 1)
                result = palindrome + remaining
            else:
                result = palindrome
            
            print(result)