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


public class Main implements Runnable {
    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

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

        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 nextLine() {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        public int nextInt() {
            int c = read();

            while(isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if(c<'0'||c>'9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

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

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }
    public static void main(String args[]) throws Exception {
        new Thread(null, new Main(),"Main",1<<26).start();
    }

    static long gcd(long a,long b){ if(b==0)return a;return gcd(b,a%b); }
    static long modPow(long a,long p,long m){ if(a==1)return 1;long ans=1;while (p>0){ if(p%2==1)ans=(ans*a)%m;a=(a*a)%m;p>>=1; }return ans; }
    static long modInv(long a,long m){return modPow(a,m-2,m);}
    static long sol_x,sol_y,gcd_a_b;
    static void extendedEuclid(long a,long b){ if(b==0){gcd_a_b=a;sol_x=1;sol_y=0; } else{ extendedEuclid(b,a%b);long temp = sol_x;sol_x=sol_y;sol_y = temp - (a/b)*sol_y; } }
    static class Bhavansort{ Random random;Bhavansort(int a[]){ randomArray(a); sort(a);}Bhavansort(long a[]){ randomArray(a); sort(a);}static int[] sort(int a[]){ Arrays.sort(a);return a;}static long[] sort(long a[]){ Arrays.sort(a);return a; }void randomArray(long a[]){ int n=a.length;for(int i=0;i<n;i++){ int p=random.nextInt(n)%n;long tm=a[i];a[i]=a[p];a[p]=tm; } }void randomArray(int a[]){ int n=a.length;for(int i=0;i<n;i++){ int p=random.nextInt(n)%n;int tm=a[i];a[i]=a[p];a[p]=tm; } }}

    public void run() {
        InputReader sc = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);

        char a[]=(" "+sc.next()).toCharArray();
        char b[]=(" "+sc.next()).toCharArray();

        int n=a.length;
        int m=b.length;

        int dp[][]=new int[n][m];
        if(a[n-1]==b[m-1])dp[n-1][m-1]=1;
        for (int i = n-2; i >=1 ; i--) {
            dp[i][m-1]=Math.max(dp[i+1][m-1],(a[i]==b[m-1]?1:0));
        }
        for (int i = m-2; i >=1 ; i--) {
            dp[n-1][i]=Math.max(dp[n-1][i+1],(a[n-1]==b[i]?1:0));
        }


        for (int i = n-2; i >=1 ; i--) {
            for (int j =m-2; j >=1 ; j--) {
                if(a[i]==b[j]){
                    dp[i][j]=1+dp[i+1][j+1];
                }
                else{
                    dp[i][j]=Math.max(dp[i+1][j],dp[i][j+1]);
                }
            }
        }


        int i=1,j=1;
        StringBuilder ans=new StringBuilder("");
        while (i<n && j<m){
         //   out.println(i+" "+j);
            if(a[i]==b[j]){
                ans.append(a[i]);
                i++;
                j++;
            }
            else{
                if(i+1<n && j+1<m&& dp[i+1][j]>=dp[i][j+1]){
                    i++;
                }
                else if(j+1<m && i+1<n && dp[i][j+1]>dp[i+1][j]){
                    j++;
                }
                else if(i+1<n && j+1>=m){
                    i++;
                }
                else if(i+1>=n && j+1<m)j++;
                else
                    break;
            }
        }

        out.println(ans);
        //out.println(dp[1][1]);

        out.close();
    }


    class Node{
        int w;long c;
        public Node(int a,long b){
            w=a;
            c=b;
        }
    }

}

Measured memory_bytes: 84820