#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define SZ(a) ((int)a.size())
#define pb push_back
#define ALL(v) v.begin(), v.end()

const ll BS = 880301;
const ll M1 = 1'000'000'007;
const ll M2 = 1'000'000'009;

const ll N = 4e6 + 5;

void build(const string &s, pii *h) {
    h[0] = {0, 0};
    for (int i = 1; i <= SZ(s); i++) {
        h[i].X = (h[i - 1].X * BS + s[i - 1]) % M1;
        h[i].Y = (h[i - 1].Y * BS + s[i - 1]) % M2;
    }
}

ll pw1[N], pw2[N];
pii get(pii *h, int l, int r) {
    pii ret;
    ret.X = (h[r].X - h[l - 1].X * pw1[r - l + 1] % M1 + M1) % M1;
    ret.Y = (h[r].Y - h[l - 1].Y * pw2[r - l + 1] % M2 + M2) % M2;
    return ret;
}

pii h[N], hr[N];



int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    string s, sr;

    cin >> s;
    int n = SZ(s);
    sr = s;
    reverse(ALL(sr));

    pw1[0] = pw2[0] = 1;
    for (int i = 1; i <= n; i++)
        pw1[i] = pw1[i - 1] * BS % M1, pw2[i] = pw2[i - 1] * BS % M2;

    build(s, h);
    build(sr, hr);

    auto getf = [&](int l, int r) {
        return get(h, l, r);
    };
    auto getr = [&](int l, int r) {
        return get(hr, n - r + 1, n - l + 1);   
    };

    int l = 1, r = n;
    for (int i = 1; i <= n; i++) {
        if (i - l + 1 <= r - i) {
            auto lh = getf(l, i);
            auto rh = getr(i + 1, i + (i - l + 1));
            if (lh == rh)
                l = i + 1;
        }
    }
    for (int i = r; i >= l; i--) {
        if (r - i + 1 <= i - l) {
            auto lh = getf(i, r);
            auto rh = getr(i - (r - i + 1), i - 1);
            if (lh == rh)
                r = i - 1;
        }
    }
    cout << r - l + 1 << endl;
}