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

int main() {
	std::string str;
	std::cin >> str;

	std::vector<std::vector<int> > v(str.length(),std::vector<int>(str.length(),0));

	int max = 0, maxi, maxj;
	for (int i = 0; i < str.size(); i++) {
		for (int j = 1; j <= str.size() - i; j++) {
			std::string s = str.substr(i, j);
			std::string r = s;
			std::reverse(r.begin(), r.end());
			if (s == r) {
				v[i][j - 1] = s.length();
				if (max < s.length()) {
					max = s.length();
					maxi = i;
					maxj = j - 1;
				}
			}
		}
	}

	v[maxi][maxj] = 0;
	int secondmax = 0;
	for (int i = 0; i < v.size(); i++) {
		secondmax = std::max(secondmax, *std::max_element(v[i].begin(), v[i].end()));
	}

	if(max != str.length()){
		std::cout << max << std::endl;
	} else {
		std::cout << secondmax << std::endl;
	}

	return 0;
}