#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
constexpr int N = 1e6 + 10;
int cnt[N];
namespace pam {
	int nxt[N][26], fail[N], len[N];
	int a[N], tot, cnt, lst;
	void init() {
		a[0] = -1;
		tot = lst = 1;
		len[1] = 0;
		len[0] = -1;
	}
	int getfail(int p) {
		while(a[cnt] != a[cnt - len[p] - 1]) p = fail[p];
		return p;
	}
	void ins(int c) {
		a[++ cnt] = c;
		int p = getfail(lst);
		if(!nxt[p][c]) {
			int cur = ++ tot;
			len[cur] = len[p] + 2;
			fail[cur] = nxt[getfail(fail[p])][c];
			nxt[p][c] = cur;
		}
		lst = nxt[p][c];
		::cnt[lst] ++;
	}
}
vector<int> G[N];
int main() {
	//freopen("in.txt", "r", stdin);
	ios::sync_with_stdio(false), cin.tie(0);
	string str;
	cin >> str;
	int n = str.size();
	pam::init();
	for(auto ch : str) pam::ins(ch - 'a');
	for(int i = 1; i <= pam::tot; i ++) {
		G[pam::fail[i]].emplace_back(i);
	}
	i64 mx = 0;
	function<void(int)> dfs = [&] (int u) {
		for(auto v : G[u]) {
			dfs(v);
			cnt[u] += cnt[v];
		}
		if(u > 1) mx = max(mx, 1ll * cnt[u] * pam::len[u] * pam::len[u]);
	};
	dfs(0);
	cout << mx << '\n';
	return 0;
}