#include <iostream>
using namespace std;
const int N = 5 << 16, A = 26;
int link[N], len[N], nxt[N][A], occ[N], cnt = 2, lst = 2;
char s[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; s[i] != '\0'; ++i) {
int cur = lst;
while (s[i - len[cur] - 1] != s[i]) cur = link[cur];
int &tmp = nxt[cur][s[i] - 'a'];
if (!tmp) {
tmp = ++cnt;
len[tmp] = len[cur] + 2;
if (cur != 1) {
cur = link[cur];
while (s[i - len[cur] - 1] != s[i]) cur = link[cur];
link[tmp] = nxt[cur][s[i] - 'a'];
} else link[tmp] = 2;
}
lst = tmp;
++occ[lst];
}
for (int i = cnt; i > 2; --i) occ[link[i]] += occ[i];
long long ans = 0;
for (int i = cnt; i > 2; --i) ans = max(ans, 1ll * occ[i] * len[i]);
cout << ans;
}
