from string import ascii_lowercase


def tmp(N):
    l = 0
    r = 10 ** 6
    while r - l > 1:
        m = (l + r) // 2
        M = m * 2
        if M * (M + 2) // 4 > N:
            r = m
        else:
            l = m
    return l * 2


N = int(input())
ans = ""
p, q = 0, 1

while N > 1:
    L = tmp(N)
    for i in range(L):
        if i % 2 == 0:
            ans += ascii_lowercase[p]
        else:
            ans += ascii_lowercase[q]
    N -= L * (L + 2) // 4
    p = (p + 2) % len(ascii_lowercase)
    q = (q + 2) % len(ascii_lowercase)

if N:
    ans += ascii_lowercase[p]

print(ans)