object Main {
  def main(args: Array[String]): Unit = {
    val s = new Main()
    s.solve()
    s.out.flush()
  }
}

class Main {
  import java.io._
  import java.util.StringTokenizer

  import scala.collection.mutable
  import scala.util.Sorting
  import math.{abs, max, min}
  import mutable.{ArrayBuffer, ListBuffer}
  import scala.reflect.ClassTag

  val MOD = 1000000007
  val out = new PrintWriter(System.out)

  def solve(): Unit = {
    val S, T = ns()

    val dp = Array.ofDim[Int](S.length + 1, T.length + 1)
    val last = Array.ofDim[Int](S.length + 1, T.length + 1)

    def enc(i: Int, j: Int) = i * 10000 + j
    def dec(x: Int) = {
      val i = x / 10000
      val j = x % 10000
      (i, j)
    }

    REP(S.length + 1) { i =>
      REP(T.length + 1) { j =>
        if (i == 0 || j == 0) {
          dp(i)(j) = 0
          last(i)(j) = -1
        } else if (S(i - 1) == T(j - 1)) {
          dp(i)(j) = dp(i - 1)(j - 1) + 1
          last(i)(j) = enc(i, j)
        } else {
          val a = dp(i)(j - 1)
          val b = dp(i - 1)(j)
          if (a > b) {
            dp(i)(j) = a
            last(i)(j) = last(i)(j - 1)
          } else {
            dp(i)(j) = b
            last(i)(j) = last(i - 1)(j)
          }
        }
      }
    }

    val str = new StringBuilder
    var x = last(S.length)(T.length)
    while(x != -1) {
      val (i, j) = dec(x)
      str.append(S(i - 1))
      x = last(i - 1)(j - 1) // dpの動きを逆に辿る
    }
    out.println(str.mkString.reverse)
  }

  class InputReader(val stream: InputStream) {
    private val reader = new BufferedReader(new InputStreamReader(stream), 32768)
    private var tokenizer: StringTokenizer = _

    def next(): String = {
      while (tokenizer == null || !tokenizer.hasMoreTokens)
        tokenizer = new StringTokenizer(reader.readLine)
      tokenizer.nextToken
    }

    def nextInt(): Int = next().toInt
    def nextLong(): Long = next().toLong
    def nextChar(): Char = next().charAt(0)
  }
  val sc = new InputReader(System.in)
  def ni(): Int = sc.nextInt()
  def nl(): Long = sc.nextLong()
  def nc(): Char = sc.nextChar()
  def ns(): String = sc.next()
  def ns(n: Int): Array[Char] = ns().toCharArray
  def na(n: Int, offset: Int = 0): Array[Int] = map(n)(_ => ni() + offset)
  def na2(n: Int, offset: Int = 0): (Array[Int], Array[Int]) = {
    val A1, A2 = Array.ofDim[Int](n)
    REP(n) { i =>
      A1(i) = ni() + offset
      A2(i) = ni() + offset
    }
    (A1, A2)
  }
  def nm(n: Int, m: Int): Array[Array[Int]] = {
    val A = Array.ofDim[Int](n, m)
    REP(n) { i =>
      REP(m) { j =>
        A(i)(j) = ni()
      }
    }
    A
  }
  def nal(n: Int): Array[Long] = map(n)(_ => nl())
  def nm_c(n: Int, m: Int): Array[Array[Char]] = map(n) (_ => ns(m))
  def REP(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = offset
    val N = n + offset
    while(i < N) { f(i); i += 1 }
  }
  def REP_r(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = n - 1 + offset
    while(i >= offset) { f(i); i -= 1 }
  }

  def map[@specialized A: ClassTag](n: Int, offset: Int = 0)(f: Int => A): Array[A] = {
    val res = Array.ofDim[A](n)
    REP(n)(i => res(i) = f(i + offset))
    res
  }


  def sumL(as: Array[Int]): Long = {
    var s = 0L
    REP(as.length)(i => s += as(i))
    s
  }

  def cumSum(as: Array[Int]) = {
    val cum = Array.ofDim[Long](as.length + 1)
    REP(as.length) { i =>
      cum(i + 1) = cum(i) + as(i)
    }
    cum
  }
}


Measured memory_bytes: 111368