#include<cstdio>
#include<vector>
#include<queue>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<ctime>
#include<random>
#include<array>
#include<assert.h>
#define pb emplace_back
#define mp make_pair
#define fi first
#define se second
#define dbg(x) cerr<<"In Line "<< __LINE__<<" the "<<#x<<" = "<<x<<'\n'
#define dpi(x,y) cerr<<"In Line "<<__LINE__<<" the "<<#x<<" = "<<x<<" ; "<<"the "<<#y<<" = "<<y<<'\n'
#define DE(fmt,...) fprintf(stderr, "Line %d : " fmt "\n",__LINE__,##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int>pii;
typedef pair<ll,int>pli;
typedef pair<ll,ll>pll;
typedef pair<int,ll>pil;
typedef vector<int>vi;
typedef vector<ll>vll;
typedef vector<pii>vpii;
typedef vector<pll>vpll;
template<typename T>T cmax(T &x, T y){return x=x>y?x:y;}
template<typename T>T cmin(T &x, T y){return x=x<y?x:y;}
template<typename T>
T &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();
	return r=w?-r:r;
}
template<typename T1,typename... T2>
void read(T1 &x,T2& ...y){read(x);read(y...);}
const int mod=998244353;
inline void cadd(int &x,int y){x=(x+y>=mod)?(x+y-mod):(x+y);}
inline void cdel(int &x,int y){x=(x-y<0)?(x-y+mod):(x-y);}
inline int add(int x,int y){return (x+y>=mod)?(x+y-mod):(x+y);}
inline int del(int x,int y){return (x-y<0)?(x-y+mod):(x-y);}
int qpow(int x,int y){
	int s=1;
	while(y){
		if(y&1)s=1ll*s*x%mod;
		x=1ll*x*x%mod;
		y>>=1;
	}
	return s;
}
const int N=1000010;
int n;
char s[N];
int L,tot=-1;
int len[N],ch[N][26],fail[N],las,siz[N];
inline int newnode(int x){len[++tot]=x;return tot;}
int getp(int x){
	while(s[L]!=s[L-len[x]-1])x=fail[x];
	return x;
}
void ins(int x){
	++L;
	int p=getp(x);
	if(!ch[p][x]){
		int cur=newnode(len[p]+2);
		fail[cur]=ch[getp(fail[p])][x];
		ch[p][x]=cur;
		las=cur;
	}else las=ch[p][x];
	siz[las]++;
}
vi eg[N];
void dfs(int x){
	for(auto v:eg[x])dfs(v),siz[x]+=siz[v];
}
signed main(){
	#ifdef do_while_true
//		assert(freopen("data.in","r",stdin));
//		assert(freopen("data.out","w",stdout));
	#endif
	scanf("%s",s+1);n=strlen(s+1);
	newnode(0);newnode(-1);
	fail[0]=1;
	for(int i=1;i<=n;i++)ins(s[i]-'a');
	for(int i=0;i<=tot;i++)if(i!=1)eg[fail[i]].pb(i);
	dfs(1);
	ll ans=0;
	for(int i=2;i<=tot;i++)cmax(ans,1ll*siz[i]*len[i]*len[i]);
	cout<<ans<<'\n';
    #ifdef do_while_true
//		cerr<<'\n'<<"Time:"<<1.0*clock()/CLOCKS_PER_SEC*1000<<" ms"<<'\n';
	#endif
	return 0;
}