#include <iostream>
#include <vector>
using namespace std;


int main() {
    ios_base::sync_with_stdio(false);
    string s;
    cin >> s;
    int n = (int) s.size();
    vector<int> v[26];
    for(int i = 0; i < n; i++) {
        v[s[i] - 'A'].push_back(i);
    }
    int res = 0;
    for(int i = 0; i < n; i++) {
        int c = s[i] - 'A';
        for(int k = (int) v[c].size() - 1; k >= 0; k--) {
            int p = v[c][k];
            if(p <= i) break;
            int sz = p - i + 1;
            if(sz % 4 != 0) continue;
            sz /= 4;
            bool ok = true;
            int cnt = 1;
            for(int j = i; j < i + sz; j++) {
                if(s[j] != s[i + 2 * sz - cnt] or s[j] != s[j + 2 * sz] or s[j] != s[i + 4 * sz - cnt]) {
                    ok = false;
                    break;
                }
                cnt++;
            }
            if(ok) {
                res = max(4 * sz, res);
                i = p;
                break;
            }
        }
    }
    cout << res << endl;
    return 0;
}