#include <bits/stdc++.h>
#define ll long long
#define pir pair <ll, ll>
#define mkp make_pair
#define fi first
#define se second
#define pb push_back
using namespace std;
const ll maxn = 1e6 + 10;
struct node { int fa, len, ch[26]; } a[maxn];
char s[maxn]; ll n, tot = 1, las = 1, ans, cnt[maxn];
vector <ll> to[maxn];
void ins(ll i, ll c) {
	ll p = las;
	while(s[i] ^ s[i - a[p].len - 1]) p = a[p].fa;
	if(!a[p].ch[c]) {
		ll np = ++tot; a[np].len = a[p].len + 2;
		ll x = a[p].fa;
		while(s[i] ^ s[i - a[x].len - 1]) x = a[x].fa;
		a[np].fa = a[x].ch[c], las = np;
		a[p].ch[c] = np;
	} else las = a[p].ch[c];
	++cnt[las];
}
void dfs(ll u) {
	for(ll v: to[u])
		dfs(v), cnt[u] += cnt[v];
	if(u > 1) ans = max(ans, a[u].len * a[u].len * cnt[u]);
}
int main(){
	scanf("%s", s + 1); n = strlen(s + 1);
	a[1].len = -1, a[0].fa = a[1].fa = 1;
	for(ll i = 1; i <= n; i++)
		ins(i, s[i] - 'a');
	for(ll i = 2; i <= tot; i++) to[a[i].fa].pb(i);
	dfs(0), dfs(1);
	printf("%lld", ans);
	return 0;
}