#include "bits/stdc++.h"
using namespace std;
const int MOD = 1e9 + 9, base = 37;
int32_t main() {
ios ::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
string s;
cin >> s;
int n = s.size();
map<int, int> cnt;
for (int i = 0; i < n; ++i) {
int h = 0;
for (int j = i; j < n; ++j) {
h = (1LL * h * base + (int)(s[i])) % MOD;
cnt[h]++;
}
}
long long ans = 0;
vector<vector<bool>> dp(n, vector<bool>(n));
for (int i = n - 1; ~i; --i)
for (int j = i; j < n; ++j)
if (i == j)
dp[i][j] = true;
else
dp[i][j] = (j - i + 1 == 2 ? (s[i] == s[j]) : (dp[i + 1][j - 1] and s[i] == s[j]));
for (int i = 0; i < n; ++i) {
int h = 0;
for (int j = i; j < n; ++j) {
h = (1LL * h * base + (int)(s[i])) % MOD;
if (dp[i][j])
ans = max(ans, 1LL * (int)(j - i + 1) * cnt[h]);
}
}
cout << ans;
}
