import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.io.Closeable;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) throws Exception {
        Thread thread = new Thread(null, new TaskAdapter(), "", 1 << 27);
        thread.start();
        thread.join();
    }

    static class TaskAdapter implements Runnable {
        @Override
        public void run() {
            InputStream inputStream = System.in;
            OutputStream outputStream = System.out;
            FastInput in = new FastInput(inputStream);
            FastOutput out = new FastOutput(outputStream);
            TaskF solver = new TaskF();
            solver.solve(1, in, out);
            out.close();
        }
    }

    static class TaskF {
        public void solve(int testNumber, FastInput in, FastOutput out) {
            String s = in.readString();
            String t = in.readString();
            out.println(lcs(s.toCharArray(), t.toCharArray()));
        }

        public String lcs(char[] a, char[] b) {
            int n = a.length;
            int m = b.length;
            int[][] dp = new int[n + 1][m + 1];
            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= m; j++) {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                    if (a[i - 1] == b[j - 1]) {
                        dp[i][j] = Math.max(dp[i][j], 1 + dp[i - 1][j - 1]);
                    }
                }
            }

            StringBuilder ans = new StringBuilder();
            trace(a, b, dp, n, m, ans);
            return ans.toString();
        }

        private void trace(char[] a, char[] b, int[][] dp, int i, int j,
                           StringBuilder ans) {
            if (i == 0 || j == 0) {
                return;
            }
            if (a[i - 1] == b[j - 1]) {
                trace(a, b, dp, i - 1, j - 1, ans);
                ans.append(a[i - 1]);
                return;
            }
            if (dp[i][j] == dp[i - 1][j]) {
                trace(a, b, dp, i - 1, j, ans);
            } else {
                trace(a, b, dp, i, j - 1, ans);
            }
        }

    }

    static class FastInput {
        private final InputStream is;
        private StringBuilder defaultStringBuf = new StringBuilder(1 << 13);
        private byte[] buf = new byte[1 << 13];
        private int bufLen;
        private int bufOffset;
        private int next;

        public FastInput(InputStream is) {
            this.is = is;
        }

        private int read() {
            while (bufLen == bufOffset) {
                bufOffset = 0;
                try {
                    bufLen = is.read(buf);
                } catch (IOException e) {
                    bufLen = -1;
                }
                if (bufLen == -1) {
                    return -1;
                }
            }
            return buf[bufOffset++];
        }

        public void skipBlank() {
            while (next >= 0 && next <= 32) {
                next = read();
            }
        }

        public String readString(StringBuilder builder) {
            skipBlank();

            while (next > 32) {
                builder.append((char) next);
                next = read();
            }

            return builder.toString();
        }

        public String readString() {
            defaultStringBuf.setLength(0);
            return readString(defaultStringBuf);
        }

    }

    static class FastOutput implements AutoCloseable, Closeable {
        private StringBuilder cache = new StringBuilder(10 << 20);
        private final Writer os;

        public FastOutput(Writer os) {
            this.os = os;
        }

        public FastOutput(OutputStream os) {
            this(new OutputStreamWriter(os));
        }

        public FastOutput println(String c) {
            cache.append(c).append('\n');
            return this;
        }

        public FastOutput flush() {
            try {
                os.append(cache);
                os.flush();
                cache.setLength(0);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
            return this;
        }

        public void close() {
            flush();
            try {
                os.close();
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        public String toString() {
            return cache.toString();
        }

    }
}



Measured memory_bytes: 103764