Time limit per test: 0.25 second(s) Memory limit: 262144 kilobytes
input: standard output: standard
A well-known application of suffix trees is solving the following problem: given a string, find the number of distinct substrings that the string has. For example, the string "abac" has 9 distinct substrings: "a", "b", "c", "ab", "ba", "ac", "aba", "bac", "abac".
You are faced with generating testcases for this problem.
More specifically, you should find the shortest string consisting only of lowercase English letters that has exactly the given amount n of distinct substrings. Among several shortest strings, choose the lexicographically smallest one.
First and only line of the input file contains an integer n, 1 ≤ n ≤ 300.
In the only line of the output file write the sought string.
Codeforces (c) Copyright 2010-2019 Mike Mirzayanov