import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;


class Main {

    public static void main(String[] args) {
        FastReader f = new FastReader();
        String s, t;
        s = f.nextLine(); t = f.nextLine();
        int[][] dp = new int[s.length() + 1][t.length() + 1];
        for(int i=1; i<=s.length(); ++i){
            for(int j=1; j<=t.length(); ++j){
                if(s.charAt(i-1) == t.charAt(j-1))
                    dp[i][j] = 1 + dp[i-1][j-1];
                else
                    dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            }
        }
        StringBuilder sb = new StringBuilder();
        int i=s.length();
        int j=t.length();
        while(true){
            if(i == 0 || j == 0)
                break;
            if(s.charAt(i-1) == t.charAt(j-1)){
                sb.append(t.charAt(j-1));
                j -= 1;
                i -= 1;
            }
            else{
                if(dp[i-1][j] > dp[i][j-1]){
                    i-=1;
                }
                else{
                    j-=1;
                }
            }
            if(sb.length() == dp[s.length()][t.length()])
                break;
        }
        System.out.println(sb.reverse());
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    public static int ii(FastReader fr) {
        return fr.nextInt();
    }

    static long il(FastReader fr) {
        return fr.nextLong();
    }

    static double id(FastReader fr) {
        return fr.nextDouble();
    }

    static void printArray(Object[] arr) {
        for (Object x : arr)
            print(x, " ");
        printn("");
    }

    static void print(Object s, String sep) {
        System.out.print(s + sep);
    }

    static void printn(Object s) {
        System.out.println(s);
    }

    static long[] inputArrL(int n, FastReader fr) {
        long[] arr = new long[n];
        for (int i = 0; i < n; i++)
            arr[i] = fr.nextLong();
        return arr;
    }

    static int[] inputArr(int n, FastReader fr) {
        int[] arr = new int[n];
        for (int i = 0; i < n; i++)
            arr[i] = fr.nextInt();
        return arr;
    }

    static int max(int... args) {
        int max = Integer.MIN_VALUE;
        for (int x : args) {
            max = Math.max(x, max);
        }
        return max;
    }

    static int min(int... args) {
        int min = Integer.MAX_VALUE;
        for (int x : args) {
            min = Math.min(x, min);
        }
        return min;
    }

    static long max(long... args) {
        long max = Integer.MIN_VALUE;
        for (long x : args) {
            max = Math.max(x, max);
        }
        return max;
    }

    static long min(long... args) {
        long min = Integer.MAX_VALUE;
        for (long x : args) {
            min = Math.min(x, min);
        }
        return min;
    }

    static int lenDigit(int d) {
        if (d == 0)
            return 1;
        int l = 0;
        while (d != 0) {
            l++;
            d /= 10;
        }
        return l;
    }

}



Measured memory_bytes: 130192