Z func

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

void z_function (string s) {
    int n = (int) s.length();
    string str = s;
    //reverse(str.begin(), str.end());
    for (int i = 0; i < str.length() / 2; i++) {
        swap(str[i], str[str.length() - 1 - i]);
    }
    s += '#';
    s += str;
    n = s.length();
    //cout << s << '\n';
    vector<int> z (n);
    for (int i=str.length() + 1, l=0, r=0; i<n; ++i) {
        if (i <= r)
            z[i] = min (r-i+1, z[i-l]);
        while (i + z[i] < n && s[z[i]] == s[i + z[i]]) {
            //cout << "z[i] = " << z[i] << ' ' << s[i] << ' ' << "i + z[i] = " << i +z[i] << ' ' << s[i +z[i]] << '\n';
            ++z[i];
        }
        if (i+z[i]-1 > r)
            l = i,  r = i+z[i]-1;
        //cout << z[i] << ' ';
    }

    int ans = 1;
    for (int i = str.length() + 1; i < z.size(); i++) ans = max(ans, z[i]);
    cout << ans;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    string s;
    cin >> s;
    int n = s.length();

    z_function(s);

}