#include<bits/stdc++.h> 
#define pr pair<int,int>
#define eps 1e-7
#define int long long

using namespace std;

inline int read()
{
	int x=0,f=1;char ch=getchar();
	while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
	while(isdigit(ch)){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}

const int N=1000005;
char s[N];
int len[N],tr[26][N],fail[N],val[N],tot;

void init()
{
	len[tot=1]=-1;
	fail[1]=fail[0]=1;
}

int n,last;

int getfail(int cur,int x)
{
	while(s[x-len[cur]-1]!=s[x])
		cur=fail[cur];
	return cur;
}

void ins(int x)
{
	int cur=getfail(last,x);
	if(!tr[s[x]-'a'][cur])
	{
		++tot;len[tot]=len[cur]+2;
		fail[tot]=tr[s[x]-'a'][getfail(fail[cur],x)];
		tr[s[x]-'a'][cur]=tot;
	}
	last=tr[s[x]-'a'][cur];
	val[last]++;
}

int ans;

signed main()
{
	scanf("%s",s+1);n=strlen(s+1);init();
	for(int i=1;i<=n;i++)
		ins(i);
	for(int i=tot;i>=0;i--)
		val[fail[i]]+=val[i];
	for(int i=0;i<=tot;i++)
		ans=max(ans,len[i]*len[i]*val[i]);
	printf("%lld\n",ans);
	return 0;
}