/* 
 * Author: $%U%$
 * Time: $%Y%$-$%M%$-$%D%$ $%h%$:$%m%$:$%s%$
 */
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,a,b) for(ll i=(a);i<=(b);i++)
#define per(i,a,b) for(ll i=(a);i>=(b);i--)
#define re(i,a,b) for(ll i=(a);i<(b);i++)
#define pe(i,a,b) for(ll i=(a);i>(b);i--)
#define getchar()(p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
char buf[1<<21],*p1=buf,*p2=buf;
template <typename T>
inline void read(T& r) {
	r=0;bool w=0; char ch=getchar();
	while(ch<'0'||ch>'9') w=ch=='-'?1:0,ch=getchar();
	while(ch>='0'&&ch<='9') r=r*10+(ch^48), ch=getchar();
	r=w?-r:r;
}
template <typename T>
inline void readupp(T& r){
	r=0;
	char ch=getchar();
	while(ch>'Z'||ch<'A')ch=getchar();
	r=ch;
}
template <typename T>
inline void readlow(T& r){
	r=0;
	char ch=getchar();
	while(ch>'z'||ch<'a')ch=getchar();
	r=ch;
}
template <typename T>
inline void readdig(T& r){
	r=0;
	char ch=getchar();
	while(ch>'9'||ch<'0')ch=getchar();
	r=ch-'0';
}
template <typename T>
inline void readvisi(T& r){
	r=0;
	char ch=getchar();
	while(ch>126||ch<33)ch=getchar();
	r=ch;
}
template <typename T>
inline ll readlowstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'z'||ch<'a')ch=getchar();
	while(ch<='z'&&ch>='a')r[++n]=ch-'a',ch=getchar();
	return n;
}
template <typename T>
inline ll readuppstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'Z'||ch<'A')ch=getchar();
	while(ch<='Z'&&ch>='A')r[++n]=ch-'A',ch=getchar();
	return n;
}
template <typename T>
inline ll readdigstr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>'9'||ch<'0')ch=getchar();
	while(ch<='9'&&ch>='0')r[++n]=ch-'0',ch=getchar();
	return n;
}
template <typename T>
inline ll readvisistr(T& r){
	ll n=0;
	char ch=getchar();
	while(ch>126||ch<33)ch=getchar();
	while(ch<=126&&ch>=33)r[++n]=ch,ch=getchar();
	return n;
}
const ll MOD=998244353;
ll gcd(ll A,ll B){return B?gcd(B,A%B):A;}
template<typename T>
void chkmax(T&A,T B){if(A<B)A=B;}
template<typename T>
void chkmin(T&A,T B){if(A>B)A=B;}
template<typename T>
T Madd(T A,T B){return A+B>=MOD?A+B-MOD:A+B;}
template<typename T>
T Msub(T A,T B){return A-B<0?A-B+MOD:A-B;}
template<typename T>
void MODed(T &A){A%=MOD;A+=(A<0?MOD:0);}
ll pw(ll A,ll B){
	ll res=1;
	while(B){
		if(B&1)res=res*A%MOD;
		A=A*A%MOD;
		B>>=1;
	}
	return res;
}
void _FILE(string s){
	freopen((s+".in").c_str(),"r",stdin);
	freopen((s+".out").c_str(),"w",stdout);
}
const ll N=1000003,M=3003,INF=2000000000000000007ll;
ll n,a[N];
ll ch[N][26],len[N],fail[N],lst=1,cnt=1;
ll sz[N];
ll add(ll x,ll pos){
	ll p=lst;
	while(p&&x!=a[pos-1-len[p]])p=fail[p];
	if(ch[p][x])return ch[p][x];
	ch[p][x]=++cnt;
	len[cnt]=len[p]+2;
	if(p){
		p=fail[p];
		while(p&&x!=a[pos-1-len[p]])p=fail[p];
		fail[cnt]=ch[p][x];
	}
	return cnt;
}
int main(){
	n=readlowstr(a);
	a[0]=-1;
	len[0]=-1;
	rep(i,1,n)lst=add(a[i],i),sz[lst]++;
	per(i,cnt,1)sz[fail[i]]+=sz[i];
	ll ans=0;
	rep(i,1,cnt)ans=max(ans,sz[i]*len[i]*len[i]);
	printf("%lld\n",ans);
	return 0;
}