#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
template<int SZ> struct palTree {
static const int sigma = 26;
int s[SZ], len[SZ], link[SZ], to[SZ][sigma], oc[SZ];
int n, last, sz;
palTree() {
s[n++] = -1;
link[0] = 1;
len[1] = -1;
sz = 2;
}
int get_link(int v) {
while(s[n-len[v]-2] != s[n-1]) v = link[v];
return v;
}
void add_letter(int c) {
s[n++] = c;
last = get_link(last);
if (!to[last][c]) {
len[sz] = len[last]+2;
link[sz] = to[get_link(link[last])][c];
to[last][c] = sz++;
}
last = to[last][c];
// cout << "OH " << len[last] << " " << last << " " << n << "\n";
oc[last] ++;
}
void prop() {
vpi v;
FOR(i,2,sz) v.pb({len[i],i});
sort(all(v)); reverse(all(v));
for (auto a: v) oc[link[a.s]] += oc[a.s];
}
};
palTree<300010> p;
string s;
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> s;
for (char c: s) p.add_letter(c-'a');
p.prop();
ll ans = 0;
FOR(i,2,p.sz) ans = max(ans,(ll)p.len[i]*p.oc[i]);
cout << ans;
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
