#include <bits/stdc++.h>

using namespace std;

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

int n, m;
int a[1030], b[1030];
int dp[1030][1030];

int main()
{
    in >> n >> m;
    for (int i = 1; i <= n; i++)
        in >> a[i];
    for (int i = 1; i <= m; i++)
        in >> 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]);
        }
    }

    out << dp[n][m] << '\n';

    for (int i = 1; i < n; i++) {
        if (dp[i][m] != dp[i + 1][m])
            out << a[i + 1] << " ";
    }

    return 0;
}