import java.io.*;
import java.util.*;

public class Main {
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        String a = sc.scanString();
        String b = sc.scanString();
        SolF sol = new SolF(a, b);
        sol.sol();
    }
}

class SolF {
    int la, lb;
    char[] a, b;
    int[][] best;
    StringBuilder sb;
    
    SolF(String a, String b){
        this.a = a.toCharArray();
        this.b = b.toCharArray();
        la = this.a.length;
        lb = this.b.length;
        best = new int[la+1][lb+1];
        sb = new StringBuilder();
    }
    
    void sol(){
        for(int i = 1; i <= la; ++i){
            for(int j = 1; j <= lb; ++j){
                if(a[i-1] == b[j-1]){
                    best[i][j] = best[i-1][j-1] + 1;
                }
                else
                    best[i][j] = Math.max(best[i-1][j] , best[i][j-1]);
            }
        }
        
        int i = la;
        int j = lb;
        while(i > 0 && j > 0){
            if(a[i-1] == b[j-1]) {
                sb.append(a[i-1]);
                --i;
                --j;
            }
            else {
                if(best[i-1][j] > best[i][j-1])
                    --i;
                else
                    --j;
            }
        }
        
        System.out.println(sb.reverse());
    }
}

class Scan {
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
}

Measured memory_bytes: 80864