#include<iostream>
#include<stack>
#include<string>
#include<algorithm>

using namespace std;

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

    int ans = -1;

    for(int i=0;i<s.size();i++){
        stack<char> st;
        int count = 0;

        string front = s.substr(i,s.size());
        
        for(int j=front.size()-1;j>0;j--){
            if(front[j] == s[i]) break;
            else front.pop_back(); 
        }

        
        string back = front;
        reverse(front.begin(),front.end());

        for(int j=0;j<front.size();j++){

            if(front[j] == back[j]) count++;
            
        }

        ans = max(ans,count);
        
    }

    cout<<ans<<endl;

}