A squared word is a word of the form xx, i.e., consisting of a sequence of letters repeated twice. Some examples of squared words in English are the words: couscous, murmur (= a low, continuous sound), tartar (= hardened dental plaque) and hotshots. We would like to find out, for a given word, how many letters should be removed from the word for it to become a squared word (however, not necessarily a correct English word).

입력 형식

The first line of the standard input contains an integer n (1 ≤ n ≤ 1000), denoting the length of the word. The second line contains a word consisting of n lower case English letters.

출력 형식

The first and only line of the standard output should contain a single integer - the minimal number of letters that should be removed from the word for it to become a squared word. We assume that the empty word is a correct squared word.

예제 입력

15
tachystoskopach

예제 출력

7

힌트

If we remove the letters y, s, o, s, k, o and p, we obtain a squared word tachtach. In Polish, this word represents a (not really well known) kind of a coach.