#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i = a; i < (b); i++)
#define sz(a) (int)(a).size()
using vi = vector<int>;
struct eertree {
vi s, rem;
struct node {
int len = 0, link = 0, from = 0, cnt = 0, freq = 0;
int visit = -1;
array<int, 26> to{};
};
vector<node> T;
int last, n;
int head = 1, overall = 0;
eertree(): s(1), rem(2, -1), T(2), last(0), n(1) {
s.reserve(1e6 + 5), T.reserve(1e6 + 5),
rem.reserve(1e6 + 5);
s[0] = -1;
T[0].link = T[1].link = 1;
T[1].len = -1;
T[0].cnt = T[1].cnt = 1;
}
int get_link(int v) {
while (s[n - T[v].len - 2] != s[n - 1]) v = T[v].link;
return v;
}
void update(int u, int p) {
if (u < 2) return;
auto& x = T[u];
if (p > x.visit) x.visit = p;
if (!x.cnt && (rem[x.visit] == -1 || T[rem[x.visit]].len < x.len))
rem[x.visit] = u;
}
void add(char ch) {
int c = ch - 'a';
s.push_back(c), rem.push_back(0);
n++;
last = get_link(last);
if (T[last].to[c] == 0) {
auto& nd = T.emplace_back();
nd.len = T[last].len + 2;
nd.link = T[get_link(T[last].link)].to[c];
nd.from = last;
T[last].to[c] = sz(T) - 1;
T[nd.from].cnt++, T[nd.link].cnt++;
overall++;
}
last = T[last].to[c];
T[last].freq++;
update(last, n - T[last].len);
}
void pop() {
int node = rem[head], c = s[head];
s[head++] = -1;
if (node < 2) return;
auto& nd = T[node];
if (nd.cnt || nd.visit != head - 1) return;
if (n - head + 1 == T[last].len) last = T[last].link;
overall--;
T[nd.from].to[c] = 0;
T[nd.from].cnt--, T[nd.link].cnt--;
update(nd.from, head);
update(nd.link, head - 1 + nd.len - T[nd.link].len);
}
void compute() {
for (int i = sz(T) - 1; i >= 0; i--) {
T[T[i].link].freq += T[i].freq;
}
}
};
int main(){
cin.tie(0)->sync_with_stdio(0);
string s;
cin >> s;
eertree e;
for(char c: s)e.add(c);
e.compute();
int mx = 0;
for(int i = 0; i < (int)e.T.size(); i++)mx = max(mx, e.T[i].freq*e.T[i].len);
cout << mx << '\n';
}
