#include <bits/stdc++.h>
using namespace std;
using pii = pair<int,int>;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
const int nmax = (1<<10) + 1;
int n , m , a[nmax] , b[nmax] , dp[nmax][nmax];
pii pre[nmax][nmax];
struct rem
{
    int val , i , j;
};
rem best[nmax][nmax];
void rec(int x , int y)
{
    if(x == y && x == 0) return;
    rec(pre[x][y].first,pre[x][y].second);
    fout << a[x] << ' ';
}
signed main()
{
    fin >> n >> m;
    for(int i = 1 ; i <= n ; ++i) fin >> a[i];
    for(int i = 1 ; i <= m ; ++i) fin >> b[i];
    for(int i = 1 ; i <= n ; ++i)
    {
        for(int j = 1 ; j <= m ; ++j) dp[i][j] = -1e9;
    }
    for(int i = 1 ; i <= n ; ++i)
    {
        for(int j = 1 ; j <= m ; ++j)
        {
            if(a[i] != b[j]);
            else
            {
                int mx = -1e9;
                if(i-1 >= 1 && j-1 >= 1) mx = best[i-1][j-1].val;
                if(mx+1 > 1)
                {
                    dp[i][j] = mx + 1;
                    pre[i][j] = {best[i-1][j-1].i,best[i-1][j-1].j};
                }
                else
                {
                    dp[i][j] = 1;
                    pre[i][j] = {0,0};
                }
                dp[i][j] = max(1,mx+1);
            }
            int mx = dp[i][j];
            pii to = {i,j};
            if(i-1 >= 1 && best[i-1][j].val > mx)
            {
                mx = best[i-1][j].val;
                to = {best[i-1][j].i,best[i-1][j].j};
            }
            if(j-1 >= 1 && best[i][j-1].val > mx)
            {
                mx = best[i][j-1].val;
                to = {best[i][j-1].i,best[i][j-1].j};
            }
            best[i][j] = {mx,to.first,to.second};
        }
    }
    cout << dp[n][m] << endl;
    rec(n,m);
    return 0;
}