#include <bits/stdc++.h>
#define ll long long
#define enl putchar('\n')
#define all(x) (x).begin(),(x).end()
#define debug(x) printf(" "#x":%d\n",x);
using namespace std;
const int MAXN = 1e6 + 5;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 998244353;
typedef pair<int, int> pii;
char buf[1 << 21], * p1 = buf, * p2 = buf, obuf[1 << 21], * o = obuf, of[35];
#define gc()(p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
inline ll qpow(ll a, ll n) { ll res = 1; while (n) { if (n & 1)res = res * a % mod; n >>= 1; a = a * a % mod; }return res; }
template <class T = int>inline T read() { T s = 0, f = 1; char c = gc(); for (; !isdigit(c); c = gc())if (c == '-')f = -1; for (; isdigit(c); c = gc())s = s * 10 + c - '0'; return s * f; }
inline void read(int* a, int n) { for (int i = 1; i <= n; ++i)a[i] = read(); }
inline int inal(char* s) { int n = 0; for (s[0] = gc(); !isalpha(s[0]); s[0] = gc()); for (; isalpha(s[n]); s[++n] = gc()); return s[n] = 0, n; }
inline int indi(char* s) { int n = 0; for (s[0] = gc(); !isdigit(s[0]); s[0] = gc()); for (; isdigit(s[n]); s[++n] = gc()); return s[n] = 0, n; }
inline void outd(auto* a, int n) { for (int i = 1; i <= n; ++i)printf("%d ", a[i]); enl; }
int n, m, q;
ll ans;
struct PAM {
    int siz, tot, lst;  //siz回文树大小，tot字符串处理到第几个
    int cnt[MAXN], ch[MAXN][26], len[MAXN], fail[MAXN];
    int dep[MAXN];
    //0节点是偶根，1节点是奇根
    char s[MAXN];
    PAM() { clear(); }
    int node(int l) {  // 建立一个新节点，长度为 l
        siz++;
        memset(ch[siz], 0, sizeof(ch[siz]));
        len[siz] = l;
        fail[siz] = cnt[siz] = 0;
        return siz;
    }
    void clear() {
        siz = -1;
        lst = 0;
        s[tot = 0] = '$';
        node(0);
        node(-1);
        fail[0] = 1;
    }
    int getfail(int x) {  // 找后缀回文
        while (s[tot - len[x] - 1] ^ s[tot])x = fail[x];
        return x;
    }
    int insert(int c) {
        s[++tot] = c;
        int cur = getfail(lst);
        if (!ch[cur][c]) {
            int x = node(len[cur] + 2);
            fail[x] = ch[getfail(fail[cur])][c];  //没有儿子默认指向偶根，偶根一直指向奇根
            ch[cur][c] = x;
            dep[x] = dep[fail[x]] + 1;  //fail指针的深度
        }
        lst = ch[cur][c];
        ++cnt[lst];
        return dep[lst];
    }
    vector<int> e[MAXN];
    void build() {
        for (int i = 1; i <= siz; ++i) e[fail[i]].push_back(i);
    }
    void dfs(int u) {
        for (auto v : e[u]) {
            dfs(v);
            cnt[u] += cnt[v];
        }
        ans = max(ans, 1ll * len[u] * len[u] * cnt[u]);
    }
}p;
char s[MAXN];
void solve() {
    n = inal(s + 1);
    for (int i = 1; i <= n; ++i)
        p.insert(s[i] - 'a');
    p.build();
    p.dfs(0);
    printf("%lld\n", ans);
}
signed main(signed argc, char const* argv[]) {
    clock_t c1 = clock();
#ifdef LOCAL
    freopen("in.in", "r", stdin);
    freopen("out.out", "w", stdout);
#endif
    //=============================================================
    int TxT = 1;
    // TxT = read();
    while (TxT--)
        solve();
    //=============================================================
#ifdef LOCAL
    end :
    cerr << "Time Used:" << clock() - c1 << "ms" << endl;
#endif
    return 0;
}