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

void solve() {
    std::string s;
    std::cin >> s;
    int n = s.length();

    int ans = n;
    for (int q = 0; q < 2; ++q) {
        for (int l = 0; l <= n; ++l) {
            int cost = n - l;

            for (int i = 0; i < l; ++i) {
                int j = l - i - 1;
                if (i >= j) break;
                if (s[i] != s[j]) cost += 2;
            }

            ans = std::min(ans, cost);
        }
        std::reverse(s.begin(), s.end());
    }

    std::cout << n - ans << std::endl;
}

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

    solve();

    return 0;
}