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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Linq;
using System.Collections.Generic;

namespace program
{
    class Program
    {
        static void Main()
        {
          var s = Input.ScanStr();
          for(int i=s.Length/2;i>=0;i--)
            if(s.Substring(0,i) == s.Substring(i,i)) { Out(i); return; }
        }
        static public void Out(object s) { Console.WriteLine(s); }
    }
    
    static class Input {
        static public int ScanInt() { return int.Parse(Console.ReadLine()); }
        static public uint ScanUint() { return uint.Parse(Console.ReadLine()); }
        static public double ScanDouble() { return double.Parse(Console.ReadLine()); }
        static public long ScanLong() { return long.Parse(Console.ReadLine()); }
        static public ulong ScanUlong() { return ulong.Parse(Console.ReadLine()); }
        static public int[] ScanIntArray() { return Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray(); }
        static public uint[] ScanUintArray() { return Console.ReadLine().Split().Select(x => uint.Parse(x)).ToArray(); }
        static public double[] ScanDoubleArray() { return Console.ReadLine().Split().Select(x => double.Parse(x)).ToArray(); }
        static public long[] ScanLongArray() { return Console.ReadLine().Split().Select(x => long.Parse(x)).ToArray(); }
        static public ulong[] ScanUlongArray() { return Console.ReadLine().Split().Select(x => ulong.Parse(x)).ToArray(); }

        static public string ScanStr() { return Console.ReadLine(); }
        static public string[] ScanStrArray() { return ScanStr().Split(); }
    }

    static class MyMath {
        public static int DistanceL1(int[] a, int[] b){
            if(a.Length != b.Length) return -1;
            int[] c = new int[a.Length];
            for(int i=0;i<a.Length;i++)
              c[i] = Math.Abs(a[i]-b[i]);
            return c.Sum();
        }

        public static double DistanceL2(int[] a, int[] b){
            if(a.Length != b.Length) return -1;
            int[] c = new int[a.Length];
            for(int i=0;i<a.Length;i++)
              c[i] = (a[i]-b[i])*(a[i]-b[i]);
            return Math.Sqrt(c.Sum());
        }
        public static int GCD(int a, int b)
        {
            Func<int, int, int> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static ulong GCD(ulong a, ulong b)
        {
            Func<ulong, ulong, ulong> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static int LCM(int a, int b)
        {
            return a * b / GCD(a, b);
        }
        public static ulong LCM(ulong a, ulong b)
        {
            return a * b / GCD(a, b);
        }
    }
}