#include <iostream>
#include <stdlib.h>
#include <string>
#include <algorithm>

#define filein "xauconmax.inp"
#define fileout "xauconmax.out"
using namespace std;

void input(string &s1, string &s2)
{
    getline(cin,s1);
    getline(cin,s2);
}

string process(string s1, string s2)
{
    int A[s1.length()+1][s2.length()+1];
    string s="";
    for(int i=0; i<=s2.length() ; i++) A[0][i]=0;
    for(int i=0; i<=s1.length() ; i++) A[i][0]=0;
    int max1=0;
    for(int i=1; i<=s1.length(); i++)
        for(int j=1; j<=s2.length(); j++)
            if(s1[i-1]==s2[j-1]) A[i][j]=A[i-1][j-1]+1;
            else A[i][j]=max(A[i-1][j],A[i][j-1]);

    int i=s1.length(), j=s2.length();
    while (i>=0 && j>=0)
    {
        if(A[i][j]==A[i-1][j]) i--;
        else if(A[i][j]==A[i][j-1]) j--;
            else
            {
                s+=s1[i-1];
                i--;
                j--;
            }
    }
    reverse(s.begin(),s.end()-1); // dao nguoc xau s
    return s;
}
void output(string s)
{
    cout<<s<<endl;
}
int main()
{
    string s1="",s2="";
    input(s1,s2);
    output(process(s1,s2));
    return 0;
}