#include<cstdio>
#include<cstdlib>
#include<cstring>

char str[1000010];
int n,tot,Q[1000010],qhead,tail,f[1000010],head[1000010],next[2000010],to[2000010];
long long val[2000010],dis[2000010];
char vis[1000010];

inline void add(int u,int v,long long w){
	++tot;
	to[tot]=v;
	val[tot]=w;
	next[tot]=head[u];
	head[u]=tot;
}

inline int bfs(int s){
	qhead=tail=0;
	memset(vis,0,sizeof(vis));
	for(int i=0;i<=n;i++) dis[i]=0;
	Q[tail++]=s; vis[s]=true;
	while(qhead<tail){
		int now=Q[qhead++];
		for(int p=head[now];p;p=next[p])
			if(!vis[to[p]]){
				dis[to[p]]=dis[now]+val[p];
				Q[tail++]=to[p];
				vis[to[p]]=true;
			}
	}
	int MAX=0;
	for(int i=0;i<=n;i++)
		if(dis[i]>dis[MAX])
			MAX=i;
	return MAX;
}

int main()
{
	freopen("savemzx.in","r",stdin);
	freopen("savemzx.out","w",stdout);
	scanf("%s",str); n=strlen(str);
	f[0]=0; f[1]=0;
	for(int i=1;i<=n;i++){
		int j=f[i];
		while(j&&str[j]!=str[i]) j=f[j];
		f[i+1]=(str[j]==str[i])?j+1:0;
	}
	for(int i=1;i<=n;i++){
		long long cost=1ll*(i-f[i])*(i-f[i]);
		add(i,f[i],cost);
		add(f[i],i,cost);
	}
	int st=bfs(0);
	int ans=bfs(st);
	printf("%lld",dis[ans]);
	return 0;
}