#include <algorithm>
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int m,n;
string lcs[3][1025];
string x[1025];
string y[1025];
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
int length[3][1025];

void getSeq()
{
    int ii;
    int previous;
    for(int i = 1; i <= n; i++)
    {
        ii = (i - 1) % 2 + 1;
        if(ii == 2)previous = 1;
        else previous = 2;

        for(int j = 1; j <= m; j++)
        {
            if(x[i].compare(y[j]) == 0)
            {
                lcs[ii][j] ="";
                length[ii][j] = 0;
                if(lcs[previous][j-1].length() > 0)
                {
                    lcs[ii][j] = lcs[previous][j-1];
                    lcs[ii][j].append(" ");
                    length[ii][j] = length[previous][j-1];
                }
                lcs[ii][j].append(x[i]);
                length[ii][j] = length[ii][j] + 1;
            }
            else
            {
                if(length[previous][j] > length[ii][j-1])
                {
                    lcs[ii][j] = lcs[previous][j];
                    length[ii][j] = length[previous][j];
                }
                else
                {
                    lcs[ii][j] = lcs[ii][j-1];
                    length[ii][j] = length[ii][j-1];
                }
            }
        }
    }
}

void read()
{
    in>>n>>m;
    for(int i = 1; i <= n; i++)
    {
        in>>x[i];
    }
    for(int i = 1; i <= m; i++)
    {
        in>>y[i];
    }
}

void write()
{
   out<<length[(n - 1) % 2 + 1][m]<<"\n"<<lcs[(n - 1) % 2 + 1][m];
}
int main()
{
    read();
    getSeq();
    write();
    return 0;
}