#include <bits/stdc++.h>
using namespace std;
template <typename T> void read(T &t) {
	t=0; char ch=getchar(); int f=1;
	while (ch<'0'||ch>'9') { if (ch=='-') f=-1; ch=getchar(); }
	do { (t*=10)+=ch-'0'; ch=getchar(); } while ('0'<=ch&&ch<='9'); t*=f;
}
typedef long long ll;
const int maxn=(3e6)+10;
char s[maxn];
ll ans;
struct PAM {
	int ch[maxn][26],fail[maxn],len[maxn],cnt[maxn],tot,lst;
	void init() {
		tot=1; fail[0]=fail[1]=1;
		len[0]=0; len[1]=-1;
	}
	void extend(int c,int n) {
		int p=lst,q;
		while (s[n-len[p]-1]!=s[n]) p=fail[p];
		if (!ch[p][c]) {
			tot++;
			len[tot]=len[p]+2;
			q=fail[p];
			while (s[n-len[q]-1]!=s[n]) q=fail[q];
			fail[tot]=ch[q][c];
			ch[p][c]=tot;
		}
		lst=ch[p][c]; cnt[lst]++;
	}
	void solve() {
		for (int i=tot;i>=1;i--) {
			cnt[fail[i]]+=cnt[i];
			ans=max(ans,(ll)cnt[i]*len[i]*len[i]);
		}
	}
} T;

int main() {
	T.init();
	scanf("%s",s+1);
	int n=strlen(s+1);
	for (int i=1;i<=n;i++) T.extend(s[i]-'a',i);
	T.solve();
	printf("%lld\n",ans);
	return 0;
}