#include <bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define vll vector<ll>
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define loop(_) for (int __ = 0; __ < (_); ++__)
#define pb push_back
#define f first
#define s second
#define sz(_) ((int)_.size())
#define all(_) _.begin(), _.end()
#define lb lower_bound
#define ub upper_bound
using ll = long long;
using ld = long double;
const int N = 1e6 + 7;
const ll mod = 1e9 + 7;
int n;
double dp[N];
double prefdp[N];
int suff;
struct node
{
int nxt[26];
int link = -1;
int len = 0;
int cnt = 0;
node()
{
memset(nxt, 0, sizeof nxt);
}
int &operator[](int x)
{
return nxt[x];
}
};
vector<node> eer;
string st;
bool extend(int pos)
{
int cur = suff;
while (1)
{
if (pos - eer[cur].len - 1 >= 0 && st[pos] == st[pos - eer[cur].len - 1])
break;
cur = eer[cur].link;
}
if (eer[cur][st[pos] - 'a'])
{
suff = eer[cur][st[pos] - 'a'];
eer[suff].cnt++;
return 0;
}
suff = sz(eer);
eer.push_back(node());
eer[cur][st[pos] - 'a'] = suff;
eer[suff].len = 2 + eer[cur].len;
eer[suff].cnt ++ ;
if (eer[suff].len == 1)
{
eer[suff].link = 1;
return 1;
}
while (true)
{
cur = eer[cur].link;
if (st[pos] == st[pos - eer[cur].len - 1])
{
eer[suff].link = eer[cur][st[pos] - 'a'];
break;
}
}
return 1;
}
void process()
{
eer.clear();
eer.push_back(node());
eer.push_back(node());
eer[0].link = eer[1].link = 0;
eer[0].len = -1, eer[1].len = 0;
suff = 1;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifndef ONLINE_JUDGE
#endif
process();
cin >> st;
n = sz(st);
for (int i = 0; i < n; ++i)
extend(i);
ll ans = 0;
priority_queue<pii> pq;
for (int i = 2; i < sz(eer); ++i)
{
pq.push({eer[i].len, i});
}
while (sz(pq))
{
pii tp = pq.top();
pq.pop();
eer[eer[tp.s].link].cnt += eer[tp.s].cnt;
}
for (int i = 1; i < sz(eer); ++i)
{
ans = max(ans, 1ll * eer[i].len * eer[i].cnt);
}
cout << ans;
return 0;
}
