#include<bits/stdc++.h>
#define ll long long
using namespace std;
const ll N=1e6;
string str;ll n,s[N+10],nd=1,las;
ll son[N+10][26],len[N+10],fail[N+10],fa[N+10],siz[N+10],ans;
void add(ll c){
	ll p=las;while(p&&s[c]!=s[c-len[p]-1])p=fail[p];
	if(!son[p][s[c]]){
		fa[++nd]=p;len[nd]=len[p]+2;
		p=nd;fail[p]=fail[fa[p]];
		while(fail[p]&&!son[fail[p]][s[c]])fail[p]=fail[fail[p]];
		fail[p]=son[fail[p]][s[c]];
		son[fa[p]][s[c]]=p;
	}else p=son[p][s[c]];las=p;
//	printf("c:%lld\n",c);
	siz[p]++;return;
}int main(){
	cin>>str;n=str.length();
	for(ll i=1;i<=n;i++)s[i]=str[i-1]-'a';
	len[0]=-1;las=1;s[0]=-1;
	for(ll i=1;i<=n;i++)add(i);
	for(ll i=nd;i>0;i--)siz[fail[i]]+=siz[i];
	for(ll i=1;i<=nd;i++)ans=max(ans,siz[i]*len[i]*len[i]);
	printf("%lld\n",ans);return 0;
}