def mask_3rd(n):
    if len(n) < 3 :
        return n
    mask_char = n[2]
    r_word = ""
    for i in range(len(n)):
        if n[i] == mask_char and i != 2 :
            r_word += "*"
        else:
            r_word += n[i]
    return r_word

print(mask_3rd("logging"))
print(mask_3rd("apple"))
print(mask_3rd("orange"))
print(mask_3rd("gooooogle"))
print(mask_3rd("i"))
print(mask_3rd("ii"))
print(mask_3rd("iii"))