import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner in = new FastScanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        String s1 = in.next();
        String s2 = in.next();
        int[][] dp = new int[s1.length() + 1][s2.length() + 1];
        for (int i = 0; i <= s1.length(); i++) {
            for (int j = 0; j <= s2.length(); j++) {
                if (i == 0 || j == 0) {
                    dp[i][j] = 0;
                }
                else if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                }
                else {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                }
            }
        }

        String ans = "";
        int i = s1.length(), j = s2.length();
        while (dp[i][j] != 0) {
            if (dp[i][j] == dp[i - 1][j]) {
                i--;
            }
            else if (dp[i][j] == dp[i][j - 1]) {
                j--;
            }
            else {
                i--;
                j--;
                ans = s1.charAt(i) + ans;
            }
        }
        out.println(ans);
        out.close();

    }


    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;
        public FastScanner(InputStream i) {
            br = new BufferedReader(new InputStreamReader(i));
            st = new StringTokenizer("");
        }
        public String next() throws IOException {
            if (st.hasMoreTokens()) {
                return st.nextToken();
            }
            else
                st = new StringTokenizer(br.readLine());
            return next();
        }
        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }
        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }
        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }
        public String nextLine() throws IOException {
            if (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
                return nextLine();
            }

            String ret = "";
            while (st.hasMoreTokens()) {
                ret += st.nextToken();
            }
            return ret;
        }
        public int[] nextIntArr(int size) throws IOException {
            int[] arr = new int[size];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = nextInt();
            }
            return arr;
        }
        public long[] nextLongArr(int size) throws IOException {
            long[] arr = new long[size];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = nextLong();
            }
            return arr;
        }
        public double[] nextDoubleArr(int size) throws IOException {
            double[] arr = new double[size];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = nextDouble();
            }
            return arr;
        }
    }
}

Measured memory_bytes: 87248