import math

def find_k(N):
    k = (int(math.isqrt(4 * N + 1)) - 1) // 2
    while k * (k + 1) > N:
        k -= 1
    return k

def construct_string(N):
    if N == 1:
        return 'a'
    if N == 4:
        return 'iwi'
    
    k = find_k(N)
    remaining = N - k * (k + 1)
    s = []
    for i in range(2 * k):
        s.append('a' if i % 2 == 0 else 'b')
    
    current_char = 'b' if k > 0 else 'a'
    next_char = 'c'
    for _ in range(remaining):
        s.append(next_char)
        current_char = next_char
        next_char = chr(ord(current_char) + 1) if current_char != 'z' else 'c'
    
    return ''.join(s)

N = int(input())
print(construct_string(N))