Merkkijono

a = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p']

n = int(input())
l = 2 ** n - 1
m = ['x'] * l

s = ''
for i in range(n):
    p = 2 ** i
    m[p - 1] = a[n - i - 1]
    j = i
    while p + 2 ** (i + 1) <= l:
        m[p + 2 ** (i + 1) - 1] = a[n - i - 1]
        
        p = p + 2 ** (i + 1)


for e in m:
    s += e

print(s)

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