#include<iostream>
#include<cstring>
using namespace std;
char s[1000010];
struct tree
{
	int ch[26],len,fail,cnt;
};
int n,num=1,p=1;
tree a[1000010];
inline void insert(int x)
{
	while(s[x]!=s[x-a[p].len-1])
	{
		p=a[p].fail;
	}
	int &P=a[p].ch[s[x]-'a'];
	if(!P)
	{
		a[P=++num].len=a[p].len+2;
		if(p)
		{
			do
			{
				p=a[p].fail;
			}
			while(s[x]!=s[x-a[p].len-1]);
			a[P].fail=a[p].ch[s[x]-'a'];
		}
		else
		{
			a[P].fail=1;
		}
	}
	a[p=P].cnt++;
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>s+1;
	n=strlen(s+1),a[0].len=-1;
	for(int i=1;i<=n;i++)
	{
		insert(i);
	}
	long long ans=0;
	for(int i=num;i>1;i--)
	{
		a[a[i].fail].cnt+=a[i].cnt;
		ans=max(ans,(long long)a[i].len*a[i].len*a[i].cnt);
	}
	cout<<ans<<endl;
	return 0;
}