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

using namespace std;

int main() {

string s;
int ans = 0,l = 0,cnt;

cin >> s;

for(int i = 1;i < s.length();i++){
    l = 0;

    for(int j = 0;j+i+1 < s.length() && i-j >= 0;j++){
        if(s[i-j] == s[i+j+1]) l += 2;
    }

    ans = max(l,ans);
    l = 1;

    for(int j = 1;j+i < s.length() && i-j >=0;j++){
        if(s[i-j] == s[i+j]) l += 2;
    }

    ans = max(l,ans);
}

cout << ans << endl;

return 0;
}