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

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
	
		// Manacher O(N)
		
		int N = S.Length;
		List<char> L = new List<char>();
		L.Add('$');
		L.AddRange(String.Join("$",S.ToCharArray()));
		L.Add('$');
		var A = Manacher(L);
		
		int max = 0;
		
		//Console.WriteLine(String.Join(" ",L.ToArray()));
		//Console.WriteLine(String.Join(" ",A));
		
		for(int i=0;i<A.Length;i++){
			int len = 0;
			if(i%2 == 0){
				// odd case:    $a$b$c$b$a$
				len = A[i] - 1;
			}else{
				// even case:    $a$b$b$a$
				len = A[i] - 1;
			}
			if(len == N) len -= 2;
			max = Math.Max(max,len);
		}
		Console.WriteLine(max);
		
	}
	
	int[] Manacher(List<char> L){
		int[] Ret=new int[L.Count];
		int i=0;
		int j=0;
		while(i<L.Count){
			while(i-j>=0 && i+j <L.Count && L[i-j]==L[i+j])++j;
			Ret[i]=j;
			int k=1;
			while(i-k>=0 && i+k <L.Count && k+Ret[i-k]<j){Ret[i+k]=Ret[i-k];++k;}
			i+=k;j-=k;
		}
		return Ret;
	}
	
	String S;
	public Sol(){
		S = rs();
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);}
	static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));}
	static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));}
	static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));}
}