import sys

def mask_3rd(s):
    try:
        return s[:2].replace(s[2],"*") + s[2] + s[3:].replace(s[2],"*")
    except IndexError:
        return s

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