#完全に回文でない時に回文を作成する関数
def palindrome(sentence):
    if  sentence[-1] == sentence[-2]:
        sentence2 = sentence[::-1]
        sentence3 = sentence2[2:]
        new_sentence = sentence + sentence3
        print(new_sentence)



    else:
        sentence2 = sentence[::-1]
        sentence3 = sentence2[1:]
        new_sentence = sentence + sentence3
        print(new_sentence)


#与えられた文字列がもうすでに完全に回文か調べる関数
def check_palindrome(sentence):
    for i in range(len(sentence)):
        if sentence[i] == sentence[-(i + 1)]:
            pass


        else:
            break
    
    else:
        print(sentence)

#文字列が既に一部回文になりかかっているかどうか調べる関数

def check_palindrome2(sentence):
    for i in range(len(sentence) -2):

        if sentence[i] == sentence[i + 2] and sentence[i] == sentence[-(i + 1)]:
            break

        elif sentence[i] == sentence[i + 2]:

            if sentence[i - 1] == sentence[i + 3]:

                check_sentence = sentence[:i + 2]
                make_palindrome = check_sentence[::-1]
                make_palindrome2 = make_palindrome[1:]
                print(check_sentence + make_palindrome2)
                break

        


            else:
    
                pass

        elif sentence[i] == sentence[i+1]:
            if sentence[i-1] == sentence[i + 2]:
                check_sentence = sentence[:i + 2]
                make_palindrome = check_sentence[::-1]
                make_palindrome2 = make_palindrome[3:]
                print(check_sentence + make_palindrome2)

                break


        else:
            pass

    else:
        palindrome(sentence)


sentence = input("")

if len(sentence) >= 2:

    check_palindrome2(sentence)
    check_palindrome(sentence)

else:
    print(sentence)