#include <iostream>
#include <string>

using namespace std;

int main()
{
  string s1,s2,sLCS;
  int ** L,i,j,m,n;

   cin >>s1;
   cin >> s2;

  m  = s1.length();
  n  = s2.length();


  L = new int * [m + 1];
  for(i = 0; i <= m; i++) L[i] = new int[n + 1];


  for(i = 0; i <= m; i++) L[i][0] = 0;
  for(j = 0; j <= n; j++) L[0][j] = 0;
  for(i = 0; i < m; i++)
    for(j = 0; j < n; j++)
      if(s1[i] == s2[j])
        L[i + 1][j + 1] = 1 + L[i][j];
      else
        L[i + 1][j + 1] = max(L[i + 1][j],L[i][j + 1]);

  sLCS = ""; i = m - 1; j = n - 1;
  while((i >= 0) && (j >= 0))
    if(s1[i] == s2[j])
    {
      sLCS = s1[i] + sLCS;
      i--; j--;
    }
    else if(L[i + 1][j] > L[i][j + 1]) j--;
    else i--;
  cout <<  L[m][n] << endl;
}