#!/usr/bin/env pypy3


import itertools
import string


def generate_words(edge_char="a"):
    for mid_len in range(19):
        for chars in itertools.product(string.ascii_lowercase, repeat=mid_len):
            yield edge_char + "".join(chars) + edge_char


def main():
    n = int(input())
    for i, word in enumerate(generate_words()):
        if i < n:
            print(word)
        else:
            print(word[:-1] + "n")
            return


if __name__ == '__main__':
    main()