import copy

ab = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']

n = int(input())

# 最初はaで確定

value = ['a']
for i in range(10):
    if len(value[0]) == n:
        break
    tmp_value = copy.copy(value)
    value = []
    for v in tmp_value:
        for j in range(n):
            value.append(v + ab[j])
            if ab[j] not in v:
                break
    for v in value:
    print(v)
