#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<60;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

vector<int> Manacher(string S) {
	string s;
	
	REP(i, S.size()) {
		s += '$';
		s += S[i];
	}
	s += '$';
	
	vector<int> r(s.size());
	int i = 0, j = 0;
	
	while (i < s.size()) {
		while (i - j >= 0 && i + j < s.size() && s[i - j] == s[i + j]) ++j;
		r[i] = j;
		int k = 1;
		while (i - k >= 0 && i + k < s.size() && k + r[i - k] < j) r[i + k] = r[i - k], ++k;
		i += k; j -= k;
	}
	
	return r;
}

int even_parindrome(int p, vector<int>& r) {
	return (r[2 * p + 2] - 1) / 2;
}

int odd_parindrome(int p, vector<int>& r) {
	return (r[2 * p + 1] + 1) / 2;
}

int main() {
	string s;
	cin >> s;
	
	vector<int> r = Manacher(s); 
	
	int ans = 0;
	REP(i, s.size()) {
		chmax(ans, even_parindrome(i, r) * 2);
		chmax(ans, odd_parindrome(i, r) * 2 - 1);
	}
	
	if (ans == s.size()) ans = max(1, ans - 2);
	
	cout << ans << endl;
	
	return 0;
}