import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author prakharjain
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        FLCS solver = new FLCS();
        solver.solve(1, in, out);
        out.close();
    }

    static class FLCS {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            String s = in.next();
            String t = in.next();

            int n = s.length();
            int m = t.length();

            int[][] dp = new int[n + 1][m + 1];

            int[][] dpr = new int[n + 1][m + 1];

            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= m; j++) {
                    if (s.charAt(i - 1) == t.charAt(j - 1)) {
                        //dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                        dp[i][j] = dp[i - 1][j - 1] + 1;
                        dpr[i][j] = 3;
                    } else {
                        dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                        if (dp[i - 1][j] >= dp[i][j - 1]) {
                            dpr[i][j] = 1;
                        } else {
                            dpr[i][j] = 2;
                        }
                    }
                }
            }

            int sx = n;
            int sy = m;

            StringBuilder ans = new StringBuilder();

            while (sx > 0 && sy > 0) {
                if (dpr[sx][sy] == 1) {
                    sx--;
                } else if (dpr[sx][sy] == 2) {
                    sy--;
                } else {
                    ans.insert(0, s.charAt(sx - 1));
                    sx--;
                    sy--;
                }
            }

            out.println(ans.toString());
            // out.println(dp[n][m]);
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public String nextString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                if (Character.isValidCodePoint(c)) {
                    res.appendCodePoint(c);
                }
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public String next() {
            return nextString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(objects[i]);
            }
        }

        public void println(Object... objects) {
            print(objects);
            writer.println();
        }

        public void close() {
            writer.close();
        }

    }
}



Measured memory_bytes: 132948