#include <iostream>
#include <vector>

using std::vector;
using std::string;

int main() {
    std::ios_base::sync_with_stdio(0);
    std::cin.tie(0);
    std::cout.tie(0);
    string first_str, second_str;
    std::cin >> first_str >> second_str;
    int n = first_str.size(), m = second_str.size();
    vector<vector<bool>> get_ans1(n + 1);
    vector<vector<bool>> get_ans2(n + 1);
    vector<bool> base(m + 1, 0);
    vector<int> LCS(m + 1, 0);
    get_ans1[0] = base;
    get_ans2[0] = base;
    for (int i = 1; i <= n; ++i) {
        vector<int> temp_max_str(m+1);
        vector<bool> temp_get_ans1(m + 1);
        vector<bool> temp_get_ans2(m + 1);
        temp_max_str[0] = 0;
        temp_get_ans1[0] = 0;
        temp_get_ans2[0] = 0;
        for (int j = 1; j <= m; ++j) {
            //temp_max_str[j] = std::max(LCS[i-1][j], temp_max_str[j-1]);
            if (LCS[j] > temp_max_str[j-1]) {
                temp_max_str[j] = LCS[j];
                temp_get_ans1[j] = 0;// {false, get_ans[i-1][j].second};//2*bit(LCS[i-1][j].second, 2);
                temp_get_ans2[j] = get_ans2[i-1][j];
            } else {
                temp_max_str[j] = temp_max_str[j-1];
                temp_get_ans1[j] = temp_get_ans1[j-1];//bit(temp_max_str[j-1].second, 1);
                temp_get_ans2[j] = 0;
            }
            if (first_str[i-1] == second_str[j-1]) {
                temp_max_str[j] = std::max(temp_max_str[j], LCS[j-1] + 1);
                temp_get_ans1[j] = 1;
                temp_get_ans2[j] = 1;
            }
        }
        LCS = temp_max_str;
        get_ans1[i] = temp_get_ans1;
        get_ans2[i] = temp_get_ans2;
    }

    int cnt = 0, first = n, second = m;
    int general_size = LCS[m];
    vector<char> answer;
    while (cnt < general_size) {
        if (get_ans1[first][second] == 1 && get_ans2[first][second] == 1) {
            answer.push_back(first_str[first-1]);
            ++cnt;
            --first;
            --second;
        } else if (get_ans1[first][second] == 0 && get_ans2[first][second] == 1) {
            --first;
        } else if (get_ans1[first][second] == 1 && get_ans2[first][second] == 0) {
            --second;
        } else if (get_ans1[first][second] == 0 && get_ans2[first][second] == 0) {
            --first;
            --second;
        }
    }
    for (int i = answer.size() - 1; i >= 0; --i) {
        std::cout << answer[i];
    }
    std::cout << std::endl;
}