import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.range, std.regex, std.typecons;
import core.bitop, core.thread;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) throw new EOFException; tokens = readln.split; } auto token = tokens[0]; tokens.popFront; return token; }
int readInt() { return readToken().to!int; }
long readLong() { return readToken().to!long; }
real readReal() { return readToken().to!real; }

void chmin(T)(ref T t, in T f) { if (t > f) t = f; }
void chmax(T)(ref T t, in T f) { if (t < f) t = f; }

int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); }


int M, N;
string S, T;

void main() {
  try {
    for (; ; ) {
      S = readToken();
      T = readToken();
      M = cast(int)(S.length);
      N = cast(int)(T.length);
      auto dp = new int[][](M + 1, N + 1);
      auto prev = new int[][](M + 1, N + 1);
      foreach (x; 0 .. M + 1) foreach (y; 0 .. N + 1) {
        dp[x][y] = -1;
      }
      dp[0][0] = 0;
      foreach (x; 0 .. M + 1) foreach (y; 0 .. N + 1) {
        if (x < M) {
          if (dp[x + 1][y] < dp[x][y]) {
            dp[x + 1][y] = dp[x][y];
            prev[x + 1][y] = 0;
          }
        }
        if (y < N) {
          if (dp[x][y + 1] < dp[x][y]) {
            dp[x][y + 1] = dp[x][y];
            prev[x][y + 1] = 1;
          }
        }
        if (x < M && y < N && S[x] == T[y]) {
          if (dp[x + 1][y + 1] < dp[x][y] + 1) {
            dp[x + 1][y + 1] = dp[x][y] + 1;
            prev[x + 1][y + 1] = 2;
          }
        }
      }
      debug {
        writeln(dp[M][N]);
      }
      char[] ans;
      for (int x = M, y = N; !(x == 0 && y == 0); ) {
        switch (prev[x][y]) {
          case 0: {
            --x;
          } break;
          case 1: {
            --y;
          } break;
          case 2: {
            --x;
            --y;
            assert(S[x] == T[y]);
            ans ~= S[x];
          } break;
          default: assert(false);
        }
      }
      ans.reverse();
      writeln(ans.to!string);
    }
  } catch (EOFException e) {
  }
}
