#include <bits/stdc++.h>
using namespace std;
#define INF 1<<30
#define endl '\n'
#define maxn 100005
#define tc prllf("Case %d: ", cs)
#define tcn prllf("Case %d:\n", cs);
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;
const double PI = acos(-1.0);
#define si(x) scanf("%d",&x)
#define sii(x,y) scanf("%d %d",&x,&y)
#define siii(x,y,z) scanf("%d %d %d",&x,&y,&z)
#define sl(x) scanf("%lld",&x)
#define sll(x,y) scanf("%lld %lld",&x,&y)
#define slll(x,y,z) scanf("%lld %lld %lld",&x,&y,&z)
#define ss(ch) scanf("%s",ch)
#define pi(x) printf("%d",x)
#define pii(x,y) printf("%d %d",x,y)
#define piii(x,y,z) printf("%d %d %d",x,y,z)
#define pl(x) printf("%lld",x)
#define pll(x,y) printf("%lld %lld",x,y)
#define plll(x,y,z) printf("%lld %lld %lld",x,y,z)
#define ps(ch) printf("%s",ch)
#define F(i,a,b) for(int i= a; i <= b; i++)
#define R(i,b,a) for(int i= b; i >= a; i--)
#define REP(i,n) for(int i = 0; i < (n); i++)
#define sline(a) scanf("%[^\n]s",a)
#define Case(t) printf("Case %d:\n",t)
const ll N = 300005;
ll idx, t;
ll link[N];
ll len[N];
ll tr[N][26];
// string s;
char s[N];
ll occ[N];
void initTree()
{
memset(tr, 0, sizeof tr);
memset(link, 0, sizeof link);
memset(len, 0, sizeof len);
len[1] = -1;
link[1] = 1;
len[2] = 0;
link[2] = 1;
idx = 2;
t = 2;
}
void addletter(ll pos)
{
while (s[pos - len[t] - 1] != s[pos]) t = link[t];
ll x = link[t];
while (s[pos - len[x] - 1] != s[pos]) x = link[x];
ll c = s[pos] - 'a';
if (!tr[t][c]) {
tr[t][c] = ++idx;
len[idx] = len[t] + 2;
link[idx] = len[idx] == 1 ? 2 : tr[x][c];
}
t = tr[t][c];
occ[t]++;
}
//https://vjudge.net/problem/HDU-3948
int main()
{
/*
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
freopen("error.txt", "w", stderr);
#endif
//*/
// ll T;
// scanf("%d", &T);
// T = 1;
// for (ll cs = 1; cs <= T; cs++) {
initTree();
// cin >> s;
// s = ' ' + s;
// ll n = s.size();
scanf("%s", s + 1);
int n = strlen(s + 1);
// cerr << n << "\n";
for (ll i = 1; i <= n; i++) {
addletter(i);
}
// prllf("Case #%d: %d\n", cs, idx - 2);
// }
// for (ll i = idx; i > 2; i--)
ll ans = 0;
for (ll i = idx; i > 2; i--) {
occ[link[i]] += occ[i];
ans = max(ans, len[i] * occ[i]);
}
// cout << ans << "\n";
pl(ans);
printf("\n");
return 0;
}
