using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Numerics;
using System.IO;
using System.Runtime.InteropServices;
using static System.Math;
using static Math2;
using static io;
using static Utils;



public class CompetitiveProgramming
{

  public void Solve()
  {
    var s = Str;
    var t = Str;
    var dp = new int[s.Length + 1][];
    Tuple<int, int>[][] pre = new Tuple<int, int>[s.Length + 1][];
    for (int i = 0; i < s.Length + 1; ++i)
    {
      dp[i] = new int[t.Length + 1];
      pre[i] = new Tuple<int, int>[t.Length + 1];
    }
    for (int i = 0; i < s.Length; ++i)
    {
      for (int j = 0; j < t.Length; ++j)
      {
        if (s[i] == t[j] && dp[i + 1][j + 1] < dp[i][j] + 1)
        {
          dp[i + 1][j + 1] = dp[i][j] + 1;
          pre[i + 1][j + 1] = new Tuple<int, int>(i, j);
        }
        if (dp[i + 1][j + 1] < dp[i + 1][j])
        {
          dp[i + 1][j + 1] = dp[i + 1][j];
          pre[i + 1][j + 1] = new Tuple<int, int>(i + 1, j);
        }
        if (dp[i + 1][j + 1] < dp[i][j + 1])
        {
          dp[i + 1][j + 1] = Max(dp[i + 1][j + 1], dp[i][j + 1]);
          pre[i + 1][j + 1] = new Tuple<int, int>(i, j + 1);
        }
      }
    }
    int n = s.Length;
    int m = t.Length;
    var ans = new List<char>();
    while (n > 0 || m > 0)
    {

      var next = pre[n][m];
      if (next == null) break;
      if (next.Item1 < n && next.Item2 < m)
      {
        ans.Add(s[next.Item1]);
      }
      n = next.Item1;
      m = next.Item2;
    }
    ans.Reverse();
    Write(new string(ans.ToArray()));
  }

}


public static class Math2
{
  public const int INF = 1 << 29;
  public const long INFL = 1L << 60;
  public const long MOD = 1000000007;
  public const int MOD2 = 998244353;

  public static long Power(long a, long b, long MOD = 1000000007)//i^N
  {
    long res = 1;
    while (b > 0)
    {
      if ((b & 1) != 0) res = res * a % MOD;
      a = a * a % MOD;
      b >>= 1;
    }
    return res;
  }
  public static long Power2(long a, long b)//i^N
  {
    long res = 1;
    while (b > 0)
    {
      if ((b & 1) != 0) res = res * a;
      a = a * a;
      b >>= 1;
    }
    return res;
  }
  public static long GCD(long a, long b)
  {
    while (b > 0)
    {
      var r = a % b;
      a = b;
      b = r;
    }
    return a;
  }
  public static long LCM(long a, long b) => (b / GCD(a, b)) * a;
  public static long Comb(long n, long r, int MOD = 1000000007)
  {
    long ret = 1;
    long x = 1;
    for (long i = n; i >= n - r + 1; --i)
    {
      ret = ret / x * i;
      ret %= MOD;
      x++;
    }
    return ret;
  }
  public static long Comb2(long n, long r)
  {
    long Nume = 1;
    long Deno = 1;

    if (r > n - r) r = n - r;
    for (long i = 1; i <= r; ++i)
    {
      Deno *= i;
      Nume *= n - i + 1;
    }
    return Nume / Deno;
  }
}
public static class Utils
{

  public static void Swap<T>(ref T A, ref T B)
  {
    T x = A;
    A = B;
    B = x;
  }
  public static int DigitSum(int N)
  {
    string s = N.ToString();
    int ret = 0;
    for (int i = 0; i < s.Length; ++i) ret += s[i] - '0';
    return ret;
  }
}
class Program
{
  static void Main(string[] args)
  {
    var CompetitiveProgramming = new CompetitiveProgramming();
    CompetitiveProgramming.Solve();
  }
}
public static class io
{
  public static string Str => Console.ReadLine();
  public static string[] Strs => Str.Split(' ');
  public static long[] Longs => Strs.Select(long.Parse).ToArray();
  public static int[] Ints => Strs.Select(int.Parse).ToArray();
  public static char[] Chars => Str.ToArray();
  public static double[] Doubles => Strs.Select(double.Parse).ToArray();
  public static long Long1 => Longs[0];
  public static int Int1 => Ints[0];
  public static char Char1 => Chars[0];
  public static double Double1 => Doubles[0];
  public static long[] VerticalRead(int N) { long[] A = new long[N]; for (int i = 0; i < N; ++i) A[i] = Long1; return A; }
  public static void Write(string a) => Console.WriteLine(a);
  public static void Write(params object[] i) => Write(string.Join(" ", i));
  public static void Write<T>(IEnumerable<T> a) => Write(string.Join(" ", a));
  public static void Verticalwrite<T>(IEnumerable<T> a) { foreach (var z in a) Write(z); }
  public static void YN(bool i) { if (i) Write("Yes"); else Write("No"); }
}

Measured memory_bytes: 337252