width= 2*(2*(size-1)) + 1
str=''
highest_val = 97+size-1
if(size==1):
    print('a')
else:
    for row in range(1,2*size):
        if(row <= size): # top triangle + central line
            substr =''
            for h in range(0,row):
                substr += chr(highest_val-h)+'-'
            rsubstr = substr[::-1] # reverse of the string
            str += (substr + rsubstr[3:]).center(width,'-') +'\n'
        else:
            pass
    bottom_str=str[::-1] # reverse the whole upper triangle string + the middle line str
    str += bottom_str[width+2:] # remove the whole middle line + the newline character
    print(str)