def unique_digits(x):
    """Given a list of positive integers x. return a sorted list of all 
    elements that hasn't any even digit.

    Note: Returned list should be sorted in increasing order.
    
    For example:
    >>> unique_digits([15, 33, 1422, 1])
    [1, 15, 33]
    >>> unique_digits([152, 323, 1422, 10])
    []
    
    Example solution:
    # line 1
    odd_digit_elements = []
    # line 2
    for i in x:
        # line 3
        if any (int(c) % 2 == 1 for c in str(i)):
            # line 4
            odd_digit_elements.append(i)
    # line 5
    return sorted(odd_digit_elements)
    
    """
    # Please print out which line of the above program contains an error. E.g. if the bug is on line 4 then print 4
    # END OF CONTEXT
    print("3")
    # END OF SOLUTION

def check(candidate):

    import io
    from contextlib import redirect_stdout

    f = io.StringIO()
    with redirect_stdout(f):
        candidate([])
    out = f.getvalue().strip('\n')

    assert "3" == out
    for i in range(0, 10):
        if i != 3:
            assert str(i) != out

if __name__ == '__main__':
    check(unique_digits)
