// <DATETIME>
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pii pair<int, int>
#define fi first
#define se second
#define rep(i, x, y) for (int i = (x); i <= (y); i ++ )
#define per(i, x, y) for (int i = (x); i >= (y); i -- )
const int N = 5e5 + 5, M = 1e6 + 5;
const int inf = 1e9, mod = 998244353;
const ll INF = 1e18, RMX = 2324814;
mt19937 rd(time(0));
uniform_int_distribution<int> dist(0, RMX);

string s;

signed main(){
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    
    cin >> s; int n = s.size();
    
    int res = 0;
    rep(i, 1, n){
		int qwq = -1;
		int l = i, r = i;
		while (l >= 1 && r <= n) qwq += (s[l - 1] == s[r - 1]) * 2, l --, r ++ ;
		res = max(res, qwq);
	}
	rep(i, 1, n - 1){
		int qwq = 0;
		int l = i, r = i + 1;
		while (l >= 1 && r <= n) qwq += (s[l - 1] == s[r - 1]) * 2, l --, r ++ ;
		res = max(res, qwq);
	}
	cout << res << "\n";
}