#include <bits/stdc++.h>
#define F first
#define S second
#define PB push_back
#define MP make_pair

using namespace std;

typedef vector<int> vi;
typedef long long ll;
typedef pair<int,int> pi;

string s1 = "", s2 = "";

string pd(int posL, int posR){
    if(posL >= s1.size() || posR >= s2.size()) return "";

    string a = pd(posL+1, posR);
    string b = "";

    int newPosR = -1;
    for(int i = posR; i < s2.size(); i++){
        if(s1[posL] == s2[i]){
            newPosR = i;
            break;
        }
    }
    if(newPosR >= posR){
        b = s1[posL] + pd(posL+1, newPosR+1);
    }
    //cout << a << " " << b << endl;
    return (a.size() > b.size()) ? a : b;
}

void solve(){
    cin >> s1 >> s2;
    if(s1.size() > s2.size()){
        string t = s1;
        s1 = s2;
        s2 = t;
    }
    cout << pd(0, 0) << endl;
}

int main(){
    solve();
    return 0;
}