#include<iostream>
#include<string>
#include<vector>
#include<algorithm>

using namespace std;

int main(){
    string s;
    cin>>s;

    int ans = -1;

    for(int i=0;i<s.size();i++){
    
        vector<string> subs;
        string front = s.substr(i,s.size());
        
        for(int j=0;j<front.size();j++){
            if(s[i] == front[j]){
                string str = front.substr(0,j+1);
                subs.push_back(str);
            }
        }

        for(int j=0;j<subs.size();j++){
            int count = 0;
            string back = subs[j];
            front = subs[j];
            reverse(back.begin(),back.end());
            for(int k=0;k<front.size();k++){
                if(front[k] == back[k]) count++;
            }
            ans = max(ans,count);

        }

        
    }

    cout<<ans<<endl;

}