/*input
www
abacabaa
*/
#include <bits/stdc++.h>
using namespace std;
const int N = 300005;
string s;
int link[N];
int val[N];
int len[N];
int adj[N][26];
int n, curNode = 1, treeSize = 1;
// 0 is even root, 1 is odd root
void build() {
memset(adj, -1, sizeof adj);
memset(link, -1, sizeof link);
len[1] = -1;
link[0] = 1, len[0] = 0;
int tmp = 0;
for(int i = 0; i < n; ++ i) {
int ch = s[i] - 'a';
for(tmp = curNode; ; tmp = link[tmp]) {
int pos = i - len[tmp] - 1;
if(pos >= 0 && s[pos] == s[i])
break;
}
if(~adj[tmp][ch]) {
curNode = adj[tmp][ch], ++ val[curNode]; continue;
}
adj[tmp][ch] = curNode = ++ treeSize;
len[curNode] = len[tmp] + 2;
if(len[curNode] == 1) {
link[curNode] = 1;
} else {
while(1) {
tmp = link[tmp];
int pos = i - len[tmp] - 1;
if(pos >= 0 && s[pos] == s[i])
break;
}
link[curNode] = adj[tmp][ch];
}
++ val[curNode];
}
}
int deg[N];
void bfs() {
for(int i = 2; i <= treeSize; ++ i) ++ deg[link[i]];
queue<int> q;
for(int i = 2; i <= treeSize; ++ i) if(deg[i] == 0) q.push(i);
while(!q.empty()) {
int u = q.front(); q.pop();
-- deg[link[u]], val[link[u]] += val[u];
if(deg[link[u]] == 0) q.push(link[u]);
}
}
int main(){
iostream::sync_with_stdio(false); cin.tie(0);
cin >> s;
n = (int)s.size();
build(), bfs();
long long Ans = 1;
for(int i = 2; i <= treeSize; ++ i) Ans = max(Ans, 1ll * len[i] * val[i]);
cout << Ans << endl;
}
