#include 
#include 
#include 
#include 
using namespace std;
string a, b;
int dp[3005][3005];
pair backtrack[3005][3005];
char bukva[3005][3005];
int rek(int i, int j) {
    if(i < 0 or j < 0) {
        return 0;
    }
    if(dp[i][j] != -1) {
        return dp[i][j];
    }
    int result = 0;
    int r1 = -10, r2 = 0, r3 = 0;
    if(a[i] == b[j]) {
        r1 =  rek(i - 1, j - 1) + 1;
    }
    r2 =  rek(i - 1, j);
    r3 =  rek(i, j - 1);
    result = max(r1, max(r2, r3));
    if(r3 == result) {
        backtrack[i][j] = make_pair(i, j - 1);
        bukva[i][j] = '.';
    }
    else if(r2 == result) {
        backtrack[i][j] = make_pair(i - 1, j);
        bukva[i][j] = '.';
    }
    else {
        
            backtrack[i][j] = make_pair(i - 1, j - 1);
            bukva[i][j] = a[i];
    }
    dp[i][j] = result;
    return result;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    cin >> a >> b;
    for(int i = 0; i < a.size(); i++) {
        for(int j = 0; j < b.size(); j++) {
            dp[i][j] = -1;
        }
    }
    if(rek((int) a.size() - 1, (int) b.size() - 1) == 0) {
        cout << "" << endl;
        return 0;
    }
    pair p = make_pair(a.size() - 1, b.size() - 1);
    string s = "";
    while(true) {
        if(p.first >= 0 and p.second >= 0) {
            s += bukva[p.first][p.second];
            p = make_pair(backtrack[p.first][p.second].first, backtrack[p.first][p.second].second);
        }
        else {
            break;
        }
    }
    for(int i = (int) s.size() - 1; i >= 0; i--) {
        if(s[i] != '.') {
            cout << s[i];
        }
    }
    return 0;
 
}