#include <bits/stdc++.h>
using namespace std;
typedef int ll;
typedef __int128 lll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pld;
#define MAX 9223372036854775807LL
#define MIN -9223372036854775807LL
#define INF 0x3f3f3f3f3f3f3f3f
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cout << fixed; cout.precision(10);
#define sp << " "
#define en << "\n"
#define compress(v) sort(v.begin(), v.end()), v.erase(unique(v.begin(), v.end()), v.end())
char a[600010];
ll len;
ll dp[600010];
struct node
{
ll adj[26] = {0, };
ll suffixlink = 0;
ll LEN = 0, COU = 0;
};
struct eertree
{
vector<node> eer;
ll pos = 0;
void init(void)
{
node tmp;
tmp.suffixlink = 0;
tmp.LEN = -1;
tmp.COU = 1;
eer.push_back(tmp);
tmp.suffixlink = 0;
tmp.LEN = 0;
tmp.COU = 1;
eer.push_back(tmp);
}
void add(ll I)
{
while(1)
{
if(I - eer[pos].LEN - 1 >= 0 && a[I] == a[I - eer[pos].LEN - 1])
break;
pos = eer[pos].suffixlink;
}
if(eer[pos].adj[a[I] - 'a'])
{
pos = eer[pos].adj[a[I] - 'a'];
eer[pos].COU++;
return;
}
node tmp;
eer[pos].adj[a[I] - 'a'] = (ll)eer.size();
tmp.LEN = eer[pos].LEN + 2;
tmp.COU = 1;
if(tmp.LEN == 1)
tmp.suffixlink = 1;
else
{
pos = eer[pos].suffixlink;
while(1)
{
if(I - eer[pos].LEN - 1 >= 0 && a[I] == a[I - eer[pos].LEN - 1])
break;
pos = eer[pos].suffixlink;
}
if(!eer[pos].adj[a[I] - 'a'])
assert(0);
tmp.suffixlink = eer[pos].adj[a[I] - 'a'];
}
pos = (ll)eer.size();
eer.push_back(tmp);
}
}eert;
vector<ll> vec[600010];
ll siz;
ll ans;
void dfs(ll here, ll pa)
{
for(auto &i : vec[here])
{
if(i == pa)
continue;
dfs(i, here);
dp[here] += dp[i];
}
}
int main(void)
{
fastio
cin >> a;
len = strlen(a);
eert.init();
for(ll i = 0 ; i < len ; i++)
eert.add(i);
siz = (ll)eert.eer.size();
for(ll i = 1 ; i < siz ; i++)
vec[eert.eer[i].suffixlink].push_back(i);
for(ll i = 0 ; i < siz ; i++)
dp[i] = eert.eer[i].COU;
dfs(0, -1);
for(ll i = 0 ; i < siz ; i++)
ans = max(ans, eert.eer[i].LEN * dp[i]);
cout << ans;
return 0;
}
