#include <iostream>
using namespace std;
int main(){
  string s;cin>>s;
  int ans = 0;
  for(int i = 0; s.size() > i; i++){
    int tmp = 1;
    //cout << s[i] << endl;
    for(int j = 1; min(i,(int)s.size()-i-1) >= j; j++){
      //cout << s[i-j] << " " << s[i+j] << endl;
      if(s[i-j] == s[i+j]){
        tmp+=2;
      }
    }
    //cout << endl;
    ans = max(ans,tmp);
    if(i){
      tmp = 0;
      if(s[i-1] == s[i])tmp = 2;
      for(int j = 1; min(i-1,(int)s.size()-i-1) >= j; j++){
        if(s[i-1-j] == s[i+j])tmp += 2;
      }
    }
    ans = max(ans,tmp);
  }
  cout << ans << endl;
}