// MagicDark
#include <bits/stdc++.h>
#define debug cerr << "\33[32m[" << __LINE__ << "]\33[m "
#define SZ(x) ((int) x.size() - 1)
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> T& chkmax(T& x, T y) {return x = max(x, y);}
template <typename T> T& chkmin(T& x, T y) {return x = min(x, y);}
template <typename T> T& read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = - f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x *= f;
}
const int N = 1e6 + 10;
int n;
string st;
struct PAM {
	int tot, son[N][26], link[N], len[N], pos[N];
	string st;
	vector <int> v[N];
	void init() {
		st = "#";
		tot = 1;
		link[0] = 1;
		len[1] = -1;
	}
	int getfail(int x) {
		while (st[SZ(st) - len[x] - 1] != st.back()) x = link[x];
		return x;
	}
	int extend(int p, char ch) {
		st += ch;
		int cur = getfail(p), c = ch - 'a';
		// debug << ch << " " << c << endl;
		if (!son[cur][c]) {
			link[++tot] = son[getfail(link[cur])][c];
			len[tot] = len[cur] + 2;
			son[cur][c] = tot;
		}
		return son[cur][c];
	}
	ll ans;
	void dfs(int x) {
		for (int i: v[x]) {
			dfs(i);
			pos[x] += pos[i];
		}
		// if ((ll) len[x] * len[x] * pos[x] == 13) debug << len[x] << endl;
		if (x > 1) chkmax(ans, (ll) len[x] * len[x] * pos[x]);
	}
	void solve() {
		F(i, 0, tot)
			if (i != 1) v[link[i]].push_back(i);
		dfs(1);
		cout << ans;
	}
} pam;
signed main() {
	pam.init();
	cin >> st;
	int num = 0;
	for (char i: st) {
		pam.pos[num = pam.extend(num, i)]++;
	}
	pam.solve();
	return 0;
}
/* why?
*/