#include <bits/stdc++.h>
using namespace std;

struct RollingHash {
    int n;
    long long base1, base2, mod1, mod2;
    vector<long long> hash1, hash2, pow1, pow2;
    RollingHash(const string &s) : base1(1009), base2(1007), mod1(1000000007), mod2(1000000009) {
        n = s.size();
        hash1.assign(n + 1, 0);
        hash2.assign(n + 1, 0);
        pow1.assign(n + 1, 1);
        pow2.assign(n + 1, 1);
        for(int i = 0; i < n; i++) {
            hash1[i + 1] = (hash1[i] + s[i]) * base1 % mod1;
            hash2[i + 1] = (hash2[i] + s[i]) * base2 % mod2;
            pow1[i + 1] = pow1[i] * base1 % mod1;
            pow2[i + 1] = pow2[i] * base2 % mod2;
        }
    }
    //[l, r)
    pair<long long, long long> get(int l, int r) {
        long long t1 = ((hash1[r] - hash1[l] * pow1[r - l]) % mod1 + mod1) % mod1;
        long long t2 = ((hash2[r] - hash2[l] * pow2[r - l]) % mod2 + mod2) % mod2;
        return {t1, t2};
    }
    // LCP of S[l, ..] and S[r, ..]
    int LCP(int l, int r){
        int len = n - r;
        int low = -1, high = len + 1;
        while(high - low > 1){
            int mid = (low + high) / 2;
            if(get(l, l + mid) == get(r, r + mid)) low = mid;
            else high = mid;
        }
        return low;
    }
};

vector<int> manacher(string &s){
    int i = 0, j = 0;
    vector<int> res(s.size());
    while (i < s.size()) {
        while (i - j >= 0 && i + j < s.size() && s[i - j] == s[i + j]) ++j;
        res[i] = j;
        int k = 1;
        while (i - k >= 0 && i + k < s.size() && k + res[i - k] < j) res[i + k] = res[i - k], ++k;
        i += k; j -= k;
    }
    return res;
}

int main(){
    int n, ans = 0;
    string s;
    cin >> s;
	n = s.size();
    vector<int> len = manacher(s), left(s.size()), right(s.size());
    for(int i = 0; i < len.size(); i++){
        left[i] = i - len[i] + 1;
        right[i] = i + len[i] - 1;
        len[i] = 2 * len[i] - 1;
        ans = max(ans, len[i] - 2);
    }
    string sr = s;
    reverse(sr.begin(), sr.end());
    string ssr = s + "$" + sr; 
    RollingHash rh(ssr);
    for(int i = 0; i < s.size(); i++){
        if(right[i] + 1 <= s.size() - 1){
            int rightStart = right[i] + 2;
            int leftStart = ssr.size() - 1 - (left[i] - 1);
            int lcp = rh.LCP(rightStart, leftStart);
            ans = max(ans, len[i] + 2 * lcp);
        }
        if(left[i] - 1 >= 0){
            int rightStart = right[i] + 1;
            int leftStart = ssr.size() - 1 - (left[i] - 2);
            int lcp = rh.LCP(rightStart, leftStart);
            ans = max(ans, len[i] + 2 * lcp);
        }
    }
    cout << ans << endl;
}