B'From beginning till end, this message has been waiting to be conveyed. For a given unordered multiset of n lowercase English letters ("multi" means that a letter may appear more than once), we treat all letters as strings of length 1, and repeat the following operation n xe2 x80 x89- xe2 x80 x891 times: The cost of such operation is defined to be , where f(s, xe2 x80 x89c) denotes the number of times character c appears in string s. Given a non-negative integer k, construct any valid non-empty set of no more than 100 xe2 x80 x89000 letters, such that the minimum accumulative cost of the whole process is exactly k. It can be shown that a solution always exists. The first and only line of input contains a non-negative integer k (0 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89k xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89100 xe2 x80 x89000) -- the required minimum cost. Output a non-empty string of no more than 100 xe2 x80 x89000 lowercase English letters -- any multiset satisfying the requirements, concatenated to be a string. Note that the printed string doesn 't need to be the final concatenated string. It only needs to represent an unordered multiset of letters. For the multiset { 'a ', 'b ', 'a ', 'b ', 'a ', 'b ', 'a ', 'b '}, one of the ways to complete the process is as follows: The total cost is 12, and it can be proved to be the minimum cost of the process. '...