#include <iostream>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

int main() {
  string s;
  cin >> s;

  const int n = s.size();

  int ans = 0;
  for (int i = 0; i < n; i++) {
    int cnt = 1;
    for (int j = 1; i - j >= 0 && i + j < n; j++) {
      if (s[i - j] == s[i + j]) {
        cnt += 2;
      }
    }
    ans = max(ans, cnt);
  }
  for (int i = 0; i + 1 < n; i++) {
    int cnt = 0;
    for (int j = 0; i - j >= 0 && i + 1 + j < n; j++) {
      if (s[i - j] == s[i + 1 + j]) {
        cnt += 2;
      }
    }
    ans = max(ans, cnt);
  }
  cout << ans << endl;
}