n = int(input())
ans = []
def dfs(line, mx):
    if len(line) == n:
        ans.append(line)
    else:
        for i in range(mx+1):
            line_copy = line.copy()
            line_copy.append(i)
            dfs(line_copy, mx)
        line_copy = line.copy()
        line_copy.append(mx+1)
        dfs(line_copy, mx+1)

dfs([0], 0)

figures = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]

for a in ans:
    for i in a:
        print(figures[i], end="")
    print()
