#include<bits/stdc++.h>
#define F(i,l,r) for(int i=(l),i##end=(r);i<=i##end;++i)
#define G(i,l,r) for(int i=(l),i##end=(r);i>=i##end;--i)
#define x first
#define y second
#define pii pair<int,int>
#define mp(x,y) make_pair(x,y)
#define ep emplace_back
using namespace std;
typedef long long ll;
constexpr int mod=1e9+7,N=1e6+9;
namespace PAM
{
	int ans=1,id=-1,n;
	char s[N];
	int tr[N][26];
	int len[N];
	int fail[N];
	int cnt[N];
	int node(int l)
	{
		id++;
		len[id]=l;
		fail[id]=0;
		return id;
	}
	void init()
	{
		id=-1;
		s[n=0]='\0';
		node(0);
		node(-1);
		fail[0]=1;
		ans=0;
	}

	int get_fail(int x)
	{
		while(s[n]!=s[n-len[x]-1]){x=fail[x];}
		return x;
	}
	void insert(char c)
	{
		s[++n]=c;
		ans=get_fail(ans);
		if(!tr[ans][c-'a'])
		{
			int x=node(len[ans]+2);
		    fail[x]=tr[get_fail(fail[ans])][c-'a'];
			tr[ans][c-'a']=x;
		}
		ans=tr[ans][c-'a'];
		cnt[ans]++;
	}
}
int f[N];int g[N][2];
using PAM::ans;
using PAM::len;
int main()
{
	//cin.tie(0)->sync_with_stdio(false);
	string s,t;
	cin>>s;
	PAM::init();
	int n=s.size();
	for(auto u:s) PAM::insert(u);
	ll ans=0;
	G(i,PAM::id,1) PAM::cnt[PAM::fail[i]]+=PAM::cnt[i];
	F(i,1,PAM::id)
		ans=max(ans,1ll*len[i]*PAM::cnt[i]);
	cout<<ans<<'\n';
	return 0;
}