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

	int maxLen = 0;
	for (int i = 1; i < s.length() - 2; i += 2) {
		int newLen = (i + 1) / 2;
		if (s.substring(0, newLen).equals(s.substring(newLen, i + 1))) {
			maxLen = Math.max(maxLen, newLen);
		}
	}
	System.out.println(maxLen*2);
	scanner.close();
}

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

	int[] flags = new int[26];  char[] chas = s.toCharArray();
	int num = 0;

	for (int i = 0; i < chas.length; i++) {
		flags[chas[i] - 'a']++;
	}

	for (int i = 0; i < flags.length; i++) {
		if (flags[i] > 0 && flags[i] % 2 != 0) {
			num++;
		}
	}
	System.out.println(num);
	scanner.close();
}