#include <iostream>

const long long MOD = 1e9 + 7;
const long long BASE = 29;

using namespace std;

long long power(long long b, long long e) {
    if (e == 0) return 1ll;
    long long sqrt = power(b, e / 2);
    sqrt = sqrt * sqrt % MOD;
    if (e % 2 == 1) sqrt = sqrt * b % MOD;
    return sqrt;
}

int main() {
    string dep_input;
    cin >> dep_input;
    int n = dep_input.size();
    int arr[n];
    arr[0] = 0;
    for (int i = 0; i < n; ++i) arr[i] = dep_input[i] - 'A';
    long long phash[n + 1];
    phash[0] = 0;
    for (int i = 1; i <= n; ++i) {
        phash[i] = (phash[i - 1] + arr[i - 1] * power(BASE, i - 1)) % MOD;
    }
    long long shash[n + 1];
    shash[n] = 0;
    for (int i = n - 1; i >= 0; --i) {
        shash[i] = (shash[i + 1] + arr[i] * power(BASE, n - i - 1)) % MOD;
    }
    long long antibase = power(BASE, MOD - 2);

    int l = 0;
    for (int i = 1; i < n; ++i) {
        if (i * 2 - l > n) break;
        long long hl = (phash[i] - phash[l] + MOD) % MOD * power(antibase, l) % MOD;
        long long hr = (shash[i] - shash[i * 2 - l] + MOD) % MOD * power(antibase, n - i * 2 + l) % MOD;
        if (hl == hr) {
//            cout << i << endl;
            l = i;
        }
    }
//    cout << "l = " << l << endl;
    int r = n;
    for (int i = n - 1; i >= 0; --i) {
        if (i * 2 - r < l) break;
        long long hl = (phash[i] - phash[i * 2 - r] + MOD) % MOD * power(antibase, i * 2 - r) % MOD;
        long long hr = (shash[i] - shash[r] + MOD) % MOD * power(antibase, n - r) % MOD;
        if (hl == hr) {
            r = i;
//            cout << i << endl;
        }
    }
//    cout << "r = " << r << endl;
    cout << r - l << endl;

    return 0;
}