#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const double PI = 3.1415926535897932384626433832795;
const ll MOD = 1000000007;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : abs(x); }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : abs(x); }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int f(string s, int l, int r) {
	int score = r - l + 1;

	int deleteCost = 0;
	for (int i = 0; 2 * i < score; i++) {
		if (s[l + i] == s[r - i]) {
			continue;
		}
		deleteCost += 2;
	}

	return score - deleteCost;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	string s;
	cin >> s;

	int n = s.size();
	int ans = 0;
	for (int l = 0; l < n; l++) {
		for (int r = l + 1; r < n; r++) {
			ans = max(ans, f(s, l, r));
		}
	}

	cout << ans << endl;
	return 0;
}