#include <bits/stdc++.h>
using namespace std;
class Eertree {
public:
int sz;
string S;
int suff_max;
vector<int> len;
vector<int> occ;
vector<int> link;
vector<vector<int>> to;
Eertree() : sz(2), S(), suff_max(1), len(2), occ(2), link(2), to(2, vector<int>(26, -1)) {
len[0] = -1, link[0] = 0;
len[1] = 0, link[1] = 0;
}
int NewNode() {
len.emplace_back();
occ.emplace_back();
link.emplace_back();
to.emplace_back(vector<int>(26, -1));
return sz++;
}
int Add(char c) {
S.push_back(c);
int pos = (int) S.size() - 1;
int cur = suff_max;
while (pos - 1 - len[cur] < 0 || S[pos - 1 - len[cur]] != c) {
cur = link[cur];
}
if (to[cur][c - 'a'] != -1) {
suff_max = to[cur][c - 'a'];
occ[suff_max]++;
return 0;
}
suff_max = NewNode();
occ[suff_max] = 1;
len[suff_max] = len[cur] + 2;
to[cur][c - 'a'] = suff_max;
if (len[suff_max] == 1) {
link[suff_max] = 1;
return 1;
}
cur = link[cur];
while (pos - 1 - len[cur] < 0 || S[pos - 1 - len[cur]] != c) {
cur = link[cur];
}
link[suff_max] = to[cur][c - 'a'];
return 1;
}
long long Solve(string S) {
for (int i = 0; i < (int) S.size(); i++) {
Add(S[i]);
}
long long ans = 0;
for (int i = sz - 1; i > 1; i--) {
ans = max(ans, 1ll * len[i] * occ[i]);
occ[link[i]] += occ[i];
}
return ans;
}
};
int main() {
string S;
cin >> S;
cout << Eertree().Solve(S) << "\n";
return 0;
}
