public class Main {


  private static void solve() {
    char[] s = ns();
    char[] t = ns();
    
    int n = s.length;
    int m = t.length;
    int[][] dp = new int[n + 1][m + 1];

    for (int i = 1; i <= n; i ++) {
      for (int j = 1; j <= m; j ++) {
        if (s[i - 1] == t[j - 1]) {
          dp[i][j] = Math.max(dp[i][j], dp[i - 1][j - 1] + 1);
        }
        dp[i][j] = Math.max(dp[i][j], dp[i][j - 1]);
        dp[i][j] = Math.max(dp[i][j], dp[i - 1][j]);
      }
    }
    int len = dp[n][m];
    char[] ret = new char[len];
    
    int i = n;
    int j = m;
    
    while (len > 0) {
      if (dp[i][j] == dp[i - 1][j]) {
        i --;
      } else if (dp[i][j] == dp[i][j - 1]) {
        j --;
      } else if (dp[i][j] == dp[i - 1][j - 1] + 1) {
        i --;
        j --;
        ret[-- len] = s[i];
      }
    }
    
    System.out.println(ret);
  }

  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}


Measured memory_bytes: 85112