import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringJoiner;
import java.util.StringTokenizer;
import java.util.function.IntUnaryOperator;
import java.util.function.LongUnaryOperator;

public class Main {
    static In in = new In();
    static Out out = new Out();
    static final long mod = 1000000007;
    static final long inf = 0x1fffffffffffffffL;
    static final int iinf = 0x3fffffff;
    static final int[] da = {-1, 0, 1, 0, -1, 1, 1, -1, -1};

    void solve() {
        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[][] prevX = new int[n + 1][m + 1];
        int[][] prevY = new int[n + 1][m + 1];
        for (int i = 0; i <= n; i++) {
            Arrays.fill(prevX[i], -1);
            Arrays.fill(prevY[i], -1);
        }
        for (int i = 0; i <= n; i++) {
            for (int j = 0; j <= m; j++) {
                if (i < n && j < m && s.charAt(i) == t.charAt(j) && dp[i + 1][j + 1] < dp[i][j] + 1) {
                    dp[i + 1][j + 1] = dp[i][j] + 1;
                    prevX[i + 1][j + 1] = i;
                    prevY[i + 1][j + 1] = j;
                }
                if (j < m && dp[i][j + 1] < dp[i][j]) {
                    dp[i][j + 1] = dp[i][j];
                    prevX[i][j + 1] = i;
                    prevY[i][j + 1] = j;
                }
                if (i < n && dp[i + 1][j] < dp[i][j]) {
                    dp[i + 1][j] = dp[i][j];
                    prevX[i + 1][j] = i;
                    prevY[i + 1][j] = j;
                }
            }
        }
        StringBuilder builder = new StringBuilder();
        int x = n;
        int y = m;
        int last = dp[x][y];
        while (x > 0 || y > 0) {
            int px = x;
            int py = y;
            x = prevX[px][py];
            y = prevY[px][py];
            if (x == -1 || y == -1) {
                break;
            }
            if (last != dp[x][y]) {
                builder.append(s.charAt(x));
            }
            last = dp[x][y];
        }
        out.println(builder.reverse());
    }

    public static void main(String[]$) {
        new Main().solve();
        out.flush();
    }
}

class In {
    private BufferedReader reader = new BufferedReader(new InputStreamReader(System.in), 0x10000);
    private StringTokenizer tokenizer;

    String next() {
        try {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
        } catch (IOException ignored) {
        }
        return tokenizer.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    char[][] nextCharArray(int n, int m) {
        char[][] a = new char[n][m];
        for (int i = 0; i < n; i++) {
            a[i] = next().toCharArray();
        }
        return a;
    }

    int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = nextInt();
        }
        return a;
    }

    int[] nextIntArray(int n, IntUnaryOperator op) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = op.applyAsInt(nextInt());
        }
        return a;
    }

    long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = nextLong();
        }
        return a;
    }

    long[] nextLongArray(int n, LongUnaryOperator op) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = op.applyAsLong(nextLong());
        }
        return a;
    }
}

class Out {
    private PrintWriter out = new PrintWriter(System.out);
    boolean autoFlush = false;

    void println(Object... a) {
        StringJoiner joiner = new StringJoiner(" ");
        for (Object obj : a) {
            joiner.add(String.valueOf(obj));
        }
        out.println(joiner);
        if (autoFlush) {
            out.flush();
        }
    }

    void println(int[] a) {
        StringJoiner joiner = new StringJoiner(" ");
        for (int i : a) {
            joiner.add(Integer.toString(i));
        }
        out.println(joiner);
        if (autoFlush) {
            out.flush();
        }
    }

    void println(long[] a) {
        StringJoiner joiner = new StringJoiner(" ");
        for (long i : a) {
            joiner.add(Long.toString(i));
        }
        out.println(joiner);
        if (autoFlush) {
            out.flush();
        }
    }

    void flush() {
        out.flush();
    }
}


Measured memory_bytes: 167252