import sys
import time
sys.setrecursionlimit(10 ** 6)
input = sys.stdin.readline
N = int(input())

groups = []

def dfs(s, n):
    if n == N:
        bits = [-1] * N
        for i, ss in enumerate(s):
            if bits[i] != -1:
                continue
            bits[i] = s.index(ss)
        if bits not in groups:
            groups.append(bits)
            print(s)
            return True
        return False
    f = False
    for ns in 'abcdefghijklmnopqrstuvwxyz':
        if dfs(s+ns, n+1):
            continue
        else:
            if not f:
                f = True
                continue
            return True

dfs('', 0)