#include <iostream>
#include <cstdio>
#include <numeric>
#include <algorithm>
#include <string>
#include <vector>
#include <functional>
#include <cmath>
#include <queue>

#define rep(i, a) FOR(i, 0, a)
#define FOR(i, a, b) for(int i = a; i < b; ++i)

typedef long long ll;
typedef unsigned long long ull;
typedef std::pair<int, int> P;
struct edge{ int to, time, cost; };

std::string str;
int dp[51];

int main(){
	std::cin >> str;
	dp[0] = 0;
	rep(i, str.size()){
		for (int j = i + 1; j <= str.size(); ++j){
			if (j - i == str.size())continue;
			std::string s = str.substr(i, j - i);
			if (s == std::string(s.rbegin(), s.rend()))dp[j] = std::max({ dp[j], dp[i], j - i });
		}
	}
	std::cout << dp[str.size()] << std::endl;
	return 0;
}