Problem:
Score : 200 points

Problem Statement

We will call a string that can be obtained by concatenating two equal strings an even string.
For example, xyzxyz and aaaaaa are even, while ababab and xyzxy are not.

You are given an even string S consisting of lowercase English letters.
Find the length of the longest even string that can be obtained by deleting one or more characters from the end of S.
It is guaranteed that such a non-empty string exists for a given input.

Constraints

2 \leq |S| \leq 200

S is an even string consisting of lowercase English letters.

There exists a non-empty even string that can be obtained by deleting one or more characters from the end of S.

Input

Input is given from Standard Input in the following format:

S

Output

Print the length of the longest even string that can be obtained.

Sample Input 1

abaababaab

Sample Output 1

6

abaababaab itself is even, but we need to delete at least one character.

abaababaa is not even.

abaababa is not even.

abaabab is not even.

abaaba is even. Thus, we should print its length, 6.

Sample Input 2

xxxx

Sample Output 2

2

xxx is not even.

xx is even.

Sample Input 3

abcabcabcabc

Sample Output 3

6

The longest even string that can be obtained is abcabc, whose length is 6.

Sample Input 4

akasakaakasakasakaakas

Sample Output 4

14

The longest even string that can be obtained is akasakaakasaka, whose length is 14.

Solution in Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static String Y = "Yes";
	public static String N = "No";
	public static long MOD = (long) (Math.pow(10, 9) + 7);
	public static Scanner sc = new Scanner(System.in);
	static int now = 0;

	public static void main(String[] args) {

		String s = n();
		int len = s.length();
		int ans = 0;

		for (int i = 2; i < len; i += 2) {
			int halflen = i / 2;
			if (s.substring(0, halflen).contentEquals(s.substring(halflen, i))) {
				ans = i;
			}
		}

		out(ans);

	}

	static int popcount(int n) {
		return Long.bitCount(n);
		//		for (;;) {
		//			n /= 2;
		//			debug("popcount:" + n);
		//			count++;
		//			if (n == 0) {
		//				out("popcountres=" + count);
		//				break;
		//
		//			}
		//		}
	}

	static int f(int n) {
		int count = 0;
		for (;;) {
			n = n % popcount(n);
			count++;
			if (n == 0) {
				break;
			}
		}
		return count;
	}

	/*
	 * 以下メソッド集
	 */
	static char[][] same(char[][] c, int h, int w) {
		char[][] a = new char[h][w];
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				a[i][j] = c[i][j];
			}
		}
		return a;

	}

	static int countkuro(char[][] c) {
		int count = 0;
		for (char[] cc : c) {
			for (char ccc : cc) {
				if ('#' == ccc) {
					count++;
				}
			}
		}
		return count;
	}

	static double[] sort(double[] r) {
		Arrays.sort(r);
		return r;
	}

	static void debug() {
		out("---");
	}

	static void debug(long a) {
		out("-------");
		out(a);
		out("-------");
	}

	static void debug(String a) {
		out("-------");
		out(a);
		out("-------");
	}

	static long[] sort(long[] n) {
		Arrays.sort(n);
		return n;
	}

	static int ketasuu(int n) {
		String str = "" + n;
		return str.length();
	}

	static int account(String str) {
		String target = "1";
		int count = 0;
		int len = str.length();
		for (int i = 0; i < len - 1; i++) {
			if (target.equals(str.substring(i, i + target.length()))) {
				count++;
			}
		}
		return count;
	}

	static int ni() {
		return sc.nextInt();
	}

	static long nl() {
		return sc.nextLong();
	}

	static double nd() {
		return sc.nextDouble();
	}

	static String n() {
		return sc.next();
	}

	static char[] nc() {
		return sc.next().toCharArray();
	}

	static int kaijo(int n) {
		if (n == 0 || n == 1) {
			return 1;
		} else {
			return n * kaijo(n - 1);
		}
	}

	static int fib(int n) {
		return (n == 1 || n == 0) ? n : fib(n - 2) + fib(n - 1);
	}

	static long lcm(long m, long n) {

		return m * n / gcd(m, n);
	}

	static int lcm(int m, int n) {

		return m * n / gcd(m, n);
	}

	static long gcd(long a, long b) {
		return (b == 0) ? a : gcd(b, a % b);
	}

	static int gcd(int a, int b) {
		return (b == 0) ? a : gcd(b, a % b);
	}

	static void out(String info) {
		System.out.println(info);
	}

	static void out(int info) {
		System.out.println(info);
	}

	static void out(double info) {
		System.out.println(info);
	}

	static void out(long info) {
		System.out.println(info);
	}

	static void out(char info) {
		System.out.println(info);
	}

	static void out(Object obj) {
		System.out.println(obj.toString());
	}

	static void outn(String info) {
		System.out.print(info);
	}

	static void outn(int info) {
		System.out.print(info);
	}

	static void outn(double info) {
		System.out.print(info);
	}

	static void outn(long info) {
		System.out.print(info);
	}

	static void outn(char info) {
		System.out.print(info);
	}

	static double max(double d, double e) {
		return Math.max(d, e);
	}

	static long max(long a, long b) {
		return Math.max(a, b);
	}

	static long min(long d, long e) {
		return Math.min(d, e);
	}

	static int min(int a, int b) {
		return (int) Math.min(a, b);
	}
}

class XY {
	int h;
	int c;

	XY(int h, int c) {
		this.h = h;
		this.c = c;
	}
}