#include <bits/stdc++.h>
using namespace std;
const int N = 5 << 16, A = 26;
int link[N], len[N], nxt[N][A], occ[N], v = 2, l[N], r[N];
string s;
void print(int i) {
cout << i << ": ";
for (int j = l[i]; j <= r[i]; ++j)
cout << s[j];
cout << '\n';
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> s;
len[1] = -1; link[1] = 1;
len[2] = 0; link[2] = 1;
for (int i = 0; i != int(s.size()); ++i) {
int cur = v;
while (s[i - len[cur] - 1] != s[i]) cur = link[cur];
int &tmp = nxt[cur][s[i] - 'a'];
if (!tmp) {
tmp = ++v;
len[tmp] = len[cur] + 2;
l[tmp] = i - len[cur] - 1;
r[tmp] = i;
if (cur != 1) {
cur = link[cur];
while (s[i - len[cur] - 1] != s[i]) cur = link[cur];
link[tmp] = nxt[cur][s[i] - 'a'];
// assert(link[tmp]);
} else link[tmp] = 2;
}
++occ[v];
}
for (int i = v; i > 2; --i) occ[link[i]] += occ[i];
long long ans = 0;
for (int i = 3; i <= v; ++i) ans = max(ans, 1ll * occ[i] * len[i]);
cout << ans << '\n';
// for (int i = 1; i <= v; ++i) {
// print(link[i]);
// print(i);
// cout << '\n';
// // cout << link[i] << ' ' << i << '\n';
// }
}
