#include <bits/stdc++.h>
using namespace std;
const int N=300000+100;
int sz[N], snext[N];
int child[N][27], cnt[N];
vector<int> g[N];
long long dp[N];
void dfs(int at) {
dp[at]=cnt[at];
for(int to:g[at]) {
if(to==at)continue;
dfs(to);
dp[at]+=dp[to];
}
}
int main () {
cin.tie(0)->sync_with_stdio(0);
string s;
cin >> s;
int n=s.size();
int pt=0;
sz[0]=0;
sz[1]=-1;
snext[0]=1;
snext[1]=1;
int nodecnt=2;
for(int i = 0;i<n;i++) {
int cur=pt;
while(cur!=1 and ((i-sz[cur]-1)<0 or s[i-sz[cur]-1]!=s[i]))cur=snext[cur];
int curnode=nodecnt++;
child[cur][s[i]-'a']=curnode;
pt=curnode;
sz[curnode]=sz[cur]+2;
cnt[pt]++;
if(cur==1) {
snext[curnode]=0;
}
else {
cur=snext[cur];
while(cur!=1 and ((i-sz[cur]-1)<0 or s[i-sz[cur]-1]!=s[i]))cur=snext[cur];
snext[curnode]=child[cur][s[i]-'a'];
}
g[snext[curnode]].push_back(curnode);
}
dfs(0);
long long res=0;
for(int i = 2;i<=n+2;i++) {
res=max(res, sz[i]*dp[i]);
}
cout << res << "\n";
return 0;
}
