#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int MAXN = 1e6 + 5;

namespace PAM
{
	int son[MAXN][26], len[MAXN], fail[MAXN], pcnt, s[MAXN], n;
	int insert(int u,int c)
	{
		while(s[n - len[u] - 1] != s[n]) u = fail[u];
		if(son[u][c]) return son[u][c];
		int v = ++pcnt; len[v] = len[u] + 2;
		int w = fail[u];
		while(s[n - len[w] - 1] != s[n]) w = fail[w];
		fail[v] = w;
		son[u][c] = v;
		return v;
	}
	int f[MAXN], bak[MAXN], seq[MAXN];
	ll build(char *_s,int _n)
	{
		pcnt = 1; len[0] = 0; len[1] = -1; fail[0] = 1; n = 0; s[0] = -1;
		int lst = 0;
		for(int i=1; i<=_n; ++i)
		{
			s[++n] = _s[i] - 'a';
			lst = insert(lst, s[n]);
			++f[lst];
		}
		
		for(int i=2; i<=n; ++i)
			++bak[len[i]];
		for(int i=1; i<=n; ++i)
			bak[i] += bak[i-1];
		for(int i=n; i>=2; --i)
			seq[bak[len[i]]--] = i;
		
		ll ans = 0;
		for(int i=n; i>=2; --i)
		{
			int u = seq[i];
			f[fail[u]] += f[u];
			ans = max(ans, (ll)f[u] * len[u] * len[u]);
		}
		return ans;
	}
}

char s[MAXN];

int main(void)
{
	scanf("%s",s+1);
	int n = strlen(s+1);
	
	ll ans = PAM :: build(s, n);
	printf("%lld\n",ans);
	return 0;
}