#include <bits/stdc++.h>
using namespace std;
string tempS, s;
int P[112345 * 2];
// 以 i 开头的最长回文串
int f[112345 * 2];
// 以 i 结尾的最长回文串
int g[112345 * 2];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> tempS;
    s = "^";
    s += "#";
    for (int i = 0; i < tempS.length(); i++)
        s += tempS[i], s += "#";
    s += "$";
    int n = s.length();
    // manacher
    int C, R;
    C = R = 0;
    for (int i = 1; i < n - 1; i++)
    {
        int i_mirror = 2 * C - i; // C - i_mirror = i - C
        if (R > i)
            P[i] = min(R - i, P[i_mirror]);
        else
            P[i] = 0;
        while (s[i + P[i] + 1] == s[i - P[i] - 1])
            P[i]++;
        f[i - P[i]] = max(f[i - P[i]], P[i]);
        g[i + P[i]] = max(g[i + P[i]], P[i]);
        if (i + P[i] > R)
        {
            C = i;
            R = i + P[i];
        }
    }
    for (int i = 3; i <= n - 2; i++)
        f[i] = max(f[i], f[i - 2] - 2);
    for (int i = n - 4; i >= 1; i--)
        g[i] = max(g[i], g[i + 2] - 2);
    /*
    cout << s << endl;
    for (int i = 0; i < n; i++)
        cout << P[i];
    cout << endl;
    for (int i = 0; i < n; i++)
        cout << f[i];
    cout << endl;
    for (int i = 0; i < n; i++)
        cout << g[i];
    cout << endl;
    */
    int ans = 0;
    for (int i = 1; i <= n - 2; i++)
        if (s[i] == '#' && f[i] && g[i])
            ans = max(ans, f[i] + g[i]);
    cout << ans << "\n";
    return 0;
}