#include <bits/stdc++.h>

#define clr(x) memset(x,0,sizeof (x))

#define For(i,a,b) for (int i=a;i<=b;i++)

#define Fod(i,b,a) for (int i=b;i>=a;i--)

#define pb(x) push_back(x)

#define mp(x,y) make_pair(x,y)

#define fi first

#define se second

#define _SEED_ ('C'+'L'+'Y'+'A'+'K'+'I'+'O'+'I')

#define outval(x) printf(#x" = %d\n",x)

#define outvec(x) printf("vec "#x" = ");for (auto _v : x)printf("%d ",_v);puts("")

#define outtag(x) puts("----------"#x"----------")

#define outarr(a,L,R) printf(#a"[%d...%d] = ",L,R);\

						For(_v2,L,R)printf("%d ",a[_v2]);puts("");

using namespace std;

typedef long long LL;

typedef unsigned long long ULL;

typedef vector <int> vi;

LL read(){

	LL x=0,f=0;

	char ch=getchar();

	while (!isdigit(ch))

    	f|=ch=='-',ch=getchar();

	while (isdigit(ch))

		x=(x<<1)+(x<<3)+(ch^48),ch=getchar();

	return f?-x:x;

}

const int N=300005;

int n;

char s[N];

namespace PAM{

	int len[N],Fail[N],Next[N][26];

	int size[N];

	int cnt;

	void init(){

		cnt=2;

		len[1]=-1,Fail[1]=1;

		len[2]=0,Fail[2]=1;

		clr(Next),clr(size);

	}

	void build(char *s,int n){

		init();

		s[0]='*';

		int x=1;

		For(i,1,n){

			while (s[i-len[x]-1]!=s[i])

				x=Fail[x];

			int c=s[i]-'a';

			if (Next[x][c])

				x=Next[x][c];

			else {

				int y=Next[x][c]=++cnt;

				len[y]=len[x]+2;

				if (len[y]==1)

					Fail[y]=2;

				else {

					x=Fail[x];

					while (s[i-len[x]-1]!=s[i])

						x=Fail[x];

					Fail[y]=Next[x][c];

				}

				x=y;

			}

			size[x]++;

		}

		Fod(i,cnt,1)

			size[Fail[i]]+=size[i];

	}

	LL solve(){

		LL ans=0;

		For(i,2,cnt)

			ans=max(ans,(LL)len[i]*size[i]);

		return ans;

	}

}

int main(){

	scanf("%s",s+1);

	n=strlen(s+1);

	PAM::build(s,n);

	cout<<PAM::solve()<<endl;

    return 0;

}