#include<bits/stdc++.h>
using namespace std;
string s;
int a; 
int main(){
   cin>>s;
   a=s.size();
   while(a>0){
   	if(s[0]==s[a-1]){
   		a=a/2;
   		s.substr(0,a-1);
//        cout<<a<<endl;
//        for(int j=0;j<s.size();j++){
//    	cout<<s;
//        }
//    cout<<endl;
   	}
   	else {
   	break;	
   	}
    
   }
   cout<<a;
   return 0;
}

/**************************************************************
	Problem: 1134
	User: chenjingqi
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/