#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  string s;
  cin>>s;
  int x=1;
  if(s.size()<3){
    //pass
  } else {
    vector<int> v;
    for(int i=0; i<s.size()-1; ++i){
      for(int j=i+1; j<s.size(); ++j){
        string s2=s.substr(i,j-i+1);
        for(int k=0; k<s2.size()/2; ++k){
          if(s2[k]!=s2[s2.size()-k-1]) break;
          if(k==s2.size()/2-1) v.push_back(s2.size());
        }
      } //j
    } //i
    sort(v.begin(),v.end());
    x=v[v.size()-1];
  }
  cout<<x<<endl;
  return 0;
}