#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
#define all(x) x.begin(), x.end()

using namespace std;

int man[8000006];
void manacher(string s)
{
    string t;
    for (int i = 0; i < (int)s.size(); i++)
    {
        t.push_back('$');
        t.push_back(s[i]);
    }
    t.push_back('$');
    int mx = 1;
    for (int i = 0; i < t.size(); i++)
    {
        man[i] = 1;
        man[i] = min(man[mx] + mx - i, man[2 * mx - i]);
        while (man[i] + i < t.size() && i - man[i] >= 0 && t[i + man[i]] == t[i - man[i]])
            man[i]++;
        if (i + man[i] > mx + man[mx]) mx = i;
    }
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    string s;
    cin >> s;
    int n = s.size();
    manacher(s);

    int l = 0, r = n - 1;
    for (int i = l; i < r; i++)
    {
        int len = (man[2 * i + 2]) / 2;
        if (len == 0) continue;
        if (i - l + 1 <= len && i + len <= r)
            l = i + 1;
    }
    for (int i = r - 1; i >= l; i--)
    {
        int len = (man[2 * i + 2]) / 2;
        if (len == 0) continue;
        if (l <= i - len + 1 && i + len >= r)
            r = i;
    }
    cout << r - l + 1 << '\n';
}