Good String

有一个字符串，要求删除最少的字符数量，使得每一个奇数位置的字符都不等于它后面的那个字符

Let's call (yet again) a string good if its length is even, and every character in odd position of this string is different from the next character (the first character is different from the second, the third is different from the fourth, and so on). For example, the strings good, string and xyyx are good strings, and the strings bad, aa and aabc are not good. Note that the empty string is considered good. You are given a string $ s $ , you have to delete minimum number of characters from this string so that it becomes good.

The first line contains one integer $ n $ ( $ 1 \le n \le 2 \cdot 10^5 $ ) — the number of characters in $ s $ . The second line contains the string $ s $ , consisting of exactly $ n $ lowercase Latin letters.

In the first line, print one integer $ k $ ( $ 0 \le k \le n $ ) — the minimum number of characters you have to delete from $ s $ to make it good. In the second line, print the resulting string $ s $ . If it is empty, you may leave the second line blank, or not print it at all.

4
good

0
good

4
aabc

2
ab

3
aaa

3