#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 = "";

        for(int j=i;j<s.size();j++){
            if(s[j] != s[i]){
                st.push('@');
            }
            else st.push(s[j]);
        }

        
        for(int j = s.size()-1;s[j] != s[i];j--){
            st.pop();
        }

        for(int j=i;!st.empty();j++){
            if(st.top() == s[i] || st.top() == '@'){
                front += st.top();
                if(st.top() == '@') count++;
                st.pop();
            }
            else break;
        }

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

        if(back != front) back = "";
        if(count == 1) count--;
        count = back.size()-count;

        ans = max(ans,count);
        
    }

    cout<<ans<<endl;

}