#include <bits/stdc++.h> using namespace std; const int maxn = 100005, baza = 29; const long long MOD = 998244353; int n; string s, s2; int dn1[maxn], dp1[maxn], dn2[maxn], dp2[maxn]; int h[maxn], hr[maxn], mn[maxn]; long long poc, ans; string znak = "abcdefghijklmnopqrstuvwxyz"; int add (int x, int y){ if (x + y >= MOD) return x + y - MOD; if (x + y < 0) return x + y + MOD; return x + y; } long long umn (long long x, long long y){ return (x * y) % MOD; } int ha (int x, int y){ if (x == 0) return umn(h[y], mn[n - 1 - y]); else return umn(h[y] - h[x - 1], mn[n - 1 - y]); } int har (int x, int y){ if (y == n - 1) return umn(hr[x], mn[x]); else return umn(hr[x] - hr[y + 1], mn[x]); } int main (void){ ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cin >> s; n = s.size(); s2 = s; for (int slovo = 0; slovo < 26; slovo++){ for (int pos = 0; pos < n; pos++){ s[pos] = znak[slovo]; poc = 0; h[0] = s[0] - 'a' + 1; mn[0] = 1; for (int i = 1; i < n; i++){ mn[i] = umn(mn[i - 1], baza); h[i] = add(h[i - 1], umn((s[i] - 'a' + 1), mn[i])); } hr[n - 1] = s[n - 1] - 'a' + 1; for (int i = n - 2; i >= 0; i--){ hr[i] = add(hr[i + 1], umn((s[i] - 'a' + 1), mn[n - i - 1])); } for (int i = 0; i < n; i++){ int low = 0, high = min(i, n - 1 - i), mid; while (low < high){ mid = (low + high) / 2 + 1; if (ha(i - mid, i - 1) == har(i + 1, i + mid)) low = mid; else high = mid - 1; } dn1[i] = low; low = 0, high = min(i - dn1[i] - 1, n - 2 - (dn1[i] + i)); while (low < high){ mid = (low + high) / 2 + 1; if (ha(i - dn1[i] - 1 - mid, i - dn1[i] - 2) == har(i + dn1[i] + 2, i + dn1[i] + 1 + mid)) low = mid; else high = mid - 1; } dn2[i] = low; poc += dn1[i]; //if (pos == 1 and slovo == 2) cout << dn1[i] << " " << dn2[i] << endl; } for (int i = 0; i < n - 1; i++){ int low = 0, high = min(i + 1, n - 1 - i), mid; while (low < high){ mid = (low + high) / 2 + 1; if (ha(i - mid + 1, i) == ha(i + 1, i + mid)) low = mid; else high = mid - 1; } dp1[i] = low; poc += dp1[i]; low = 0, high = min(i - dp1[i], n - 2 - (dp1[i] + i)); while (low < high){ mid = (low + high) / 2 + 1; if (ha(i - dp1[i] - mid, i - dp1[i] - 1) == ha(i + dp1[i] + 2, i + dp1[i] + 1 + mid)) low = mid; else high = mid - 1; } dp2[i] = low; //if (pos == 1 and slovo == 2) cout << dp1[i] << " " << dp2[i] << endl; } poc += n; s = s2; ans = max(ans, poc); } } cout << ans << "\n"; return 0; }