#include <bits/stdc++.h>
using namespace std;

int main() {
	string s;
	cin >> s;
	int n = s.size(), a = 0, b = 0;
	for (int i = 0; i < n; i++) {
		int puni = 1;
		for (int j = 1; j < n; j++) {
			if (i - j < 0 || n <= i + j) {
				continue;
			}
			if (s[i - j] == s[i + j]) {
				puni += 2;
			}
		}
		a = max(a, puni);
	}
	for (int i = 0; i < n; i++) {
		int puni = 0;
		for (int j = 0; j < n; j++) {
			if (i - j < 0 || n <= i + j + 1) {
				continue;
			}
			if (s[i - j] == s[i + j + 1]) {
				puni += 2;
			}
		}
		b = max(b, puni);
	}
	cout << max(a, b) << endl;
	return 0;
}