#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<string>
#include<algorithm>
#include<ctime>
#include<cmath>
#include<queue>
using namespace std;
#define FILE "savemzx"
#define pii pair<long long,long long>
#define LL long long 
#define up(i,j,n) for(int i=j;i<=n;i++)
#define down(i,n,j) for(int i=n;i>=j;i--)
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))
#define abs(x) ((x)<0?(-(x)):(x))
template<typename T>inline bool chkmax(T &a,T b){return a<b?a=b,true : false;}
template<typename T>inline bool chkmin(T &a,T b){return a>b?a=b,true : false;}
int read(){
	int x=0;char ch=getchar();bool flag=0;
	while(ch<'0'||ch>'9'){if(ch=='-')flag=1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return flag?-x:x;
}
namespace OI{
	const int maxn=1010000;
	const LL inf=10000000000000000LL;
	char s[maxn];
	int next[maxn],n;
	bool vis[maxn];
	inline LL squ(int x){return (LL)x*x;}
	struct node{
		int y,next;
		LL v;
	}e[maxn<<1];
	int linkk[maxn],len=0;
	void insert(int x,int y,LL v){
		e[++len].y=y;
		e[len].next=linkk[x];
		linkk[x]=len;
		e[len].v=v;
	}
	LL w[maxn],maxx[maxn],maxx2[maxn],child[maxn];
	int fa[maxn];
	LL ans=0;
	void dfs(int x){
		for(int i=linkk[x];i;i=e[i].next){
			if(e[i].y==fa[x])continue;
			fa[e[i].y]=x;
			dfs(e[i].y);
			chkmax(ans,e[i].v);
			w[e[i].y]+=e[i].v;
			if(w[e[i].y]>maxx[x])maxx2[x]=maxx[x],maxx[x]=w[e[i].y];
			else if(w[e[i].y]>maxx2[x])maxx2[x]=w[e[i].y];
		}
		chkmax(ans,maxx[x]+maxx2[x]);
		w[x]=maxx[x];
	}
	void slove(){
		scanf("%s",s+1);n=strlen(s+1);
		int j=0;next[1]=0;
		insert(1,0,1);insert(0,1,1);
		for(int i=2;i<=n;i++){
			while(s[i]!=s[j+1]&&j)j=next[j];
			if(s[i]==s[j+1])j++;
			next[i]=j;
			insert(j,i,squ(j-i));
			insert(i,j,squ(i-j));
		}
		dfs(0);
		printf("%lld\n",ans);
		return;
	}
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	using namespace OI;
	slove();
	return 0;
}