#include<bits/stdc++.h>
#define poly vector<int>
#define IOS ios::sync_with_stdio(false)
#define ll long long
#define mp make_pair
#define mt make_tuple
#define pa pair < int,int >
#define fi first
#define se second
#define inf 1e18
#define mod 998244353
#define sz(x) (int)((x).size())
#define int ll
//#define N
using namespace std;
const int N=1000005;
namespace PAM
{
	int tr[N][26];
	int fail[N],len[N];
	int cnt,lst;
	int siz[N];
	void init()
	{
		cnt=1;
		fail[0]=1;
		len[1]=-1;
	}
	void build(string s)
	{
		for (int i=0,lst=0;i<sz(s);i++)
		{
			while (!(i-len[lst]-1>=0&&s[i-len[lst]-1]==s[i]))
			{
				lst=fail[lst];
			}
			if (!tr[lst][s[i]-'a'])
			{
				++cnt;
				len[cnt]=len[lst]+2;
				int x=fail[lst];
				while (s[i-len[x]-1]!=s[i]) x=fail[x];
				fail[cnt]=tr[x][s[i]-'a'];
				tr[lst][s[i]-'a']=cnt;
			}
			lst=tr[lst][s[i]-'a'];
			siz[lst]++;
		}
	}
	void calc()
	{
		int ans=0;
		for (int i=cnt;i>=2;i--)
			siz[fail[i]]+=siz[i],ans=max(ans,siz[i]*len[i]*len[i]);
		cout<<ans<<'\n';
	}
}	
void BellaKira()
{
	string s;
	cin>>s;
	PAM::init();
	PAM::build(s);
	PAM::calc();
}
signed main()
{
	IOS;
	cin.tie(0);
	int T=1;
	while (T--)
	{
		BellaKira();
	}
}