#include<bits/stdc++.h>
#define Gc() getchar()
#define Me(x,y) memset(x,y,sizeof(x))
#define Mc(x,y) memcpy(x,y,sizeof(x))
#define d(x,y) ((m)*(x-1)+(y))
#define R(n) (rnd()%(n)+1)
#define Pc(x) putchar(x)
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define eb emplace_back
#define all(x) x.begin(),x.end()
using namespace std;using ll=long long;using db=double;using lb=long db;using ui=unsigned;using ull=unsigned ll;using pii=pair<int,int>;
const int N=1e6+5,M=N*30+5,K=1000+5,mod=1e9+7,Mod=mod-1;const db eps=1e-9;const ll INF=1e18+7;mt19937 rnd(time(0));
#define Tp template<typename T>
#define Ts template<typename T,typename... Ar>
namespace Debug{
	Tp void _debug(char* f,T t){cerr<<f<<'='<<t<<endl;}
	Ts void _debug(char* f,T x,Ar... y){while(*f!=',') cerr<<*f++;cerr<<'='<<x<<",";_debug(f+1,y...);}
	#ifdef LOCAL
	#define gdb(...) _debug((char*)#__VA_ARGS__,__VA_ARGS__)
	#else 
	#define gdb(...) void()
	#endif
}using namespace Debug;
int n;char s[N];
namespace PAM{
	int siz[N],son[N][26],len[N],cnt=1,La=1,link[N];
	int jump(int x,int id){while(x^1&&s[id-len[x]-1]^s[id]) x=link[x];return x;}
	ll ans=0;
	vector<int> S[N];
	void dfs(int x,int La){
		for(int i:S[x]) dfs(i,x),siz[x]+=siz[i];
		if(x^1) ans=max(ans,1ll*siz[x]*len[x]*len[x]);
	}
	void build(){
		len[0]=0;len[1]=-1;link[0]=1;
		for(int i=1;i<=n;i++){
			int p=jump(La,i);
			if(!son[p][s[i]-'a']){
				len[++cnt]=len[p]+2;
				link[cnt]=son[jump(link[p],i)][s[i]-'a'];
				son[p][s[i]-'a']=cnt;
			}
			p=son[p][s[i]-'a'];siz[p]++;La=p;
		}
		for(int i=0;i<=cnt;i++) if(i^1) S[link[i]].push_back(i);
		dfs(1,0);
		printf("%lld\n",ans);
	}
}
void Solve(){
	scanf("%s",s+1);n=strlen(s+1);
	PAM::build();
}
int main(){
	int t=1;
	// scanf("%d",&t);
	while(t--) Solve();
	cerr<<clock()*1.0/CLOCKS_PER_SEC<<'\n';
}