#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define rep(i, a, b) for (auto i = (a); i < (b); ++i)
#define trav(e, x) for (auto &e : x)
#define eb(x...) emplace_back(x)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
template<class T> bool ckmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
const int A = 26;
using pnode = struct node*;
struct node {
int len, occ; pnode link, nxt[A];
node() : occ{0}, link{nullptr} { fill(nxt, nxt + A, nullptr); }
};
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
string s; cin >> s;
vector<pnode> nodes;
pnode zero, imag, last;
imag = new node();
imag->len = -1;
imag->link = imag;
zero = new node();
zero->len = 0;
zero->link = imag;
last = zero;
rep(i, 0, sz(s)) {
pnode cur = last;
while (s[i - cur->len - 1] != s[i]) cur = cur->link;
auto &tmp = cur->nxt[s[i] - 'a'];
if (!tmp) {
tmp = new node();
tmp->len = cur->len + 2;
if (cur != imag) {
cur = cur->link;
while (s[i - cur->len - 1] != s[i]) cur = cur->link;
tmp->link = cur->nxt[s[i] - 'a'];
} else tmp->link = zero;
nodes.eb(tmp);
}
last = tmp;
++last->occ;
}
reverse(all(nodes));
trav(v, nodes) v->link->occ += v->occ;
ll ans = 0;
trav(v, nodes) ckmax(ans, 1ll * v->len * v->occ);
cout << ans;
}
