def add_string(str1): 

        length = len(str1) 

        if length > 2: 

                if str1[-3:] == 'ing':
                        str1 += 'ly' 

        else: 

                str1 += 'ing' 


        return str1 

#string less than 3 = remain unchanged 

print('String less than 3 - UNCHANGED:')
print(add_string('ab'))
print('\nAdd ing at last - + ing:') 

print(add_string('abc')) 

print('\nalready ending with ing - + ly:') 

print(add_string('string'))