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

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int A[1026], B[1026], D[1026][1026], sir[1026], n, m, cnt, maxim;

void read(int n, int v[])
{
    for(int i = 1; i<=n; i++)
        fin >> v[i];
}

void LCS(int i, int j)
{
    for(i = 1; i<=n; i++)
    {
        for(j = 1; j<=m; j++)
        {
         if(A[i] == B[j])
                D[i][j] = 1 + D[i-1][j-1];
            else
                D[i][j] = max(D[i-1][j], D[i][j-1]);
        }
    }
    maxim = D[n][m];
    fout << maxim << "\n";
    i--;
    j--;
    while(maxim)
    {
        if(D[i][j-1] == maxim)
            j--;
        else
        {
            sir[++cnt] = B[j];
            i--;
            j--;
            maxim--;
        }
    }
}

int main()
{
    fin >> n >> m;
    read(n, A);
    read(m, B);
    LCS(1,1);
    for(int i = cnt; i>=1; i--)
        fout << sir[i] <<' ';
    return 0;
}