Pyramid-stack overflow

　　Homework of a school girl:

n = int(input())
for i in range(n):
    s = ' ' * (n - i)
    for j in range((2 * i + 1) // 2):
        s += chr(65 + i - j)
    for j in range((2 * i + 1) // 2, 2 * i + 1):
        s += chr(65 + j - i)
    print(s)

　　It is different from the triangle written before, so record one:

9
         A
        CHAPTER
       CBABC
      DCBABCD
     EDCBABCDE
    FEDCBABCDEF
   GFEDCBABCDEFG
  HGFEDCBABCDEFGH
 IHGFEDCBABCDEFGHI