#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<ctime>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef pair<int,int> pii;
const int maxn=3e5+10;
const int maxm=1e6+10;
const ll mod=1e9+7;
const ll base=1e8;
const ull base1=10007;
const ull base2=19260817;
const int maxxn=0x3f3f3f3f;
const int minxn=-0x3f3f3f3f;
const db inf=1e13;
const db eps=1e-9;
inline int read(){
    int x=0,w=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')w=-1;c=getchar();}
    while(c<='9'&&c>='0'){x=(x<<3)+(x<<1)+c-'0';c=getchar();}
    return x*w;
}
int n;
char s[maxn];
struct PAM{
	int ch[maxn][26],fail[maxn],len[maxn],tot,last;
	int cnt[maxn];
	inline void init(){
		tot=1;
		fail[0]=fail[1]=1,len[1]=-1;
	}
	inline int get_fail(int u,int i){
		while(i-len[u]-1<1||s[i-len[u]-1]!=s[i]) u=fail[u];
		return u;
	}
	inline void insert(int i){
		int u=get_fail(last,i),c=s[i]-'a';
		if(!ch[u][c]){
			int f=get_fail(fail[u],i);
			fail[++tot]=ch[f][c],ch[u][c]=tot,len[tot]=len[u]+2;
		}
		last=ch[u][c];
		++cnt[last];
	}
	inline ll get_ans(){
		ll res=0;
		for(int i=tot;i>=0;--i) cnt[fail[i]]+=cnt[i];
		for(int i=2;i<=tot;++i) res=max(res,1ll*len[i]*cnt[i]);
		return res;
	}
}P;
int main(){
	scanf("%s",s+1);
	n=strlen(s+1);
	P.init();
	for(int i=1;i<=n;++i) P.insert(i);
	printf("%lld\n",P.get_ans());
	return 0;
}