#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);
    }
    else {
    break;  
    }
      
   }
   cout<<a;
   return 0;
}
/**************************************************************
	Problem: 1134
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2076 kb
****************************************************************/