import java.util.Scanner;

public class ABB {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int length = sc.nextInt();
        sc.nextLine();
        String input = sc.nextLine();
        StringBuilder sb = new StringBuilder(input);
        String revInput = sb.reverse().toString();

        char[] in = input.toCharArray();

        if (input.equals(revInput)) {
            System.out.println(0);
            System.exit(0);
        }

        for (int k=1; k<length; ++k) {
            boolean sameShit = true;
            for (int i = 0; i < in.length-k; i++) {
                if (in[i+k] != in[length-i-1]) {
                    sameShit = false;
                    break;
                }
            }
            if (sameShit) {
                System.out.println(k);
                System.exit(0);
            }
        }

    }

}