#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    string s; cin >> s;
    int n = int(s.size()), ans = 1;
    rep(i,n) {
        int cnt = 0;
        rep(k,n) if(0 <= i - k && i + k < n)
            cnt += (s[i - k] == s[i + k]);
        ans = max(ans, cnt * 2 - 1);
    }

    rep(i,n) {
        int cnt = 0;
        rep(k,n) if(k) if(0 <= i - k && i + k - 1 < n) 
            cnt += (s[i - k] == s[i + k - 1]);
        ans = max(ans, cnt * 2);
    }

    cout << ans << endl;
}