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
            for ii in range(i+1, N):
                if s[ii] == ss:
                    bits[ii] = i
        if bits not in groups:
            groups.append(bits)
            print(s)
        return
    for ns in 'abcdefghijklmnopqrstuvwxyz'[:n+1]:
        dfs(s+ns, n+1)

dfs('', 0)
