#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
N = int(read())


# %%
def count_palindrome(N):
    x = N // 2
    y = N - x
    return (x + 1) * x // 2 + (y + 1) * y // 2


# %%
def f(N, alphabets):
    if N == 0:
        return ''
    left = 0
    right = 10 ** 9
    while left + 1 < right:
        x = (left + right) // 2
        if count_palindrome(x) <= N:
            left = x
        else:
            right = x
    x = left
    S = (''.join(alphabets[:2])) * (x // 2 + 5)
    return S[:x] + f(N - count_palindrome(x), alphabets[2:])


# %%
alphabets = [chr(ord('a') + x) for x in range(26)]
answer = f(N, alphabets)
print(answer)