class RepeatStringEasy {
public:
    vector<vector<vector<int>>> cache;
    int _maximal(int l, int m, int r);
    int maximalLength(string);
    string s;
};

int RepeatStringEasy::_maximal(int l, int m, int r) {
    if (l >= m)
        return 0;
    if (l == s.size() || r == s.size())
        return 0;

    if (cache[l][m][r] >= 0)
        return cache[l][m][r];

    int& result = cache[l][m][r];
    if (s[l] == s[r]) {
        result = _maximal(l+1, m, r+1) + 2;
        return result;
    }
    result = max(_maximal(l+1, m, r), _maximal(l, m, r+1));
    return result;
}

int RepeatStringEasy::maximalLength(string s) {
    cache = vector<vector<vector<int>>>(50, vector<vector<int>>(50, vector<int>(50, -1)));
    int ret = 0;
    for (int i = 0; i < s.size(); ++i)
        ret = max(ret, _maximal(0, i, i));
    return ret;
}