Merkkijono

n = int(input())
n -= 1

def check():
    alphabet = (['b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'])
    if n == -1:
        return ''
    if n == 0:
        return 'a'
    final = ['a']
    for i in range(n):
        final.insert(0, alphabet[i])
        p = 0
        while p <= len(final) - 3:
            if final[p] != final[p + 2] and final[p] == alphabet[i]:
                final.insert(p + 2, alphabet[i])
            p += 1
    final.extend(list(reversed(final[:len(final) - 1:])))
    new = str()
    for i in final:
        new += i
    return new


print(check())

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