/* Author: goats_9 */
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct eertree {
enum { K = 26, A = 'a' };
struct Node {
vector<int> nxt = vector<int> (K, -1);
ll len = 0, cnt = 0;
int suf = 0;
Node() = default;
};
vector<Node> tree;
eertree() : tree(2, Node()) { tree[0].len = -1; }
eertree(string s) : eertree() {
int p = 1, n = (int)s.size();
for (int i = 0; i < n; i++) {
while (i <= tree[p].len || s[i] != s[i - tree[p].len - 1]) p = tree[p].suf;
if (tree[p].nxt[s[i] - A] == -1) {
tree[p].nxt[s[i] - A] = (int)tree.size();
tree.push_back(Node());
tree.back().len = tree[p].len + 2;
}
int q = tree[p].nxt[s[i] - A];
if (tree[q].len == 1) {
tree[q].suf = 1;
tree[q].cnt++;
p = q;
continue;
}
p = tree[p].suf;
while (i <= tree[p].len || s[i] != s[i - tree[p].len - 1]) p = tree[p].suf;
tree[q].suf = tree[p].nxt[s[i] - A];
tree[q].cnt++;
p = q;
}
for (int i = (int)tree.size() - 1; i >= 0; i--) tree[tree[i].suf].cnt += tree[i].cnt;
}
};
int main() {
string s;
cin >> s;
eertree tr(s);
ll ans = 0;
for (auto u : tr.tree) ans = max(ans, u.len * u.cnt);
cout << ans;
return 0;
}
