Merkkijono

n = int(input())

s = "a"
step = 0

from string import ascii_lowercase


for i in range(1, n):
    if n==2:
        s = s[:0] + ascii_lowercase[i] + s[0:] + ascii_lowercase[i]
        
    elif i==1:
        s = s[:0] + ascii_lowercase[i] + s[0:] + ascii_lowercase[i]
    elif n>2 and i>1:
        for _ in range(len(s)+1):
            s = s[:step] + ascii_lowercase[i] + s[step:]
            step += 2
    step=0


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