Merkkijono

n = int(input())

aakkoset = "abcdefghijklmnopqrs"

lista = ["a"]
lista_str = ""

for i in range (n-1):
	for q in range (2**(i+1)):
		lista.insert(2*q,aakkoset[i+1])

for i in range (len(lista)):
	lista_str = lista_str + lista[i]

print(lista_str)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED