#include <iostream>
#include <fstream>
#include <string.h>

using namespace std;

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

const int maxn = 1030;

int n, m, a[maxn], b[maxn], dp[maxn][maxn];

inline void reconstr(int x, int y) {
    if(!x || !y)
        return ;
    if(a[x] == b[y]) {
        reconstr(x - 1, y - 1);
        fout << a[x] << ' ';
        return ;
    }
    if(dp[x - 1][y] > dp[x][y - 1])
        reconstr(x - 1, y);
    else
        reconstr(x, y - 1);
}

int 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)
            if(a[i] == b[j])
                dp[i][j] = dp[i - 1][j - 1] + 1;
            else
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
    fout << dp[n][m] << '\n';
    reconstr(n, m);
}