#include <bits/stdc++.h>

using namespace std;

#define int long long

#define MAXN 200005

int a[1030], b[1030], prec[1030];

int dp[1025][1025];

vector <int> ans;

int n, m, last;

ifstream fin("cmlsc.in");

ofstream fout("cmlsc.out");

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++){

        if (b[j] == a[i])

            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";

    while (n && m){



        if (a[n] == b[m]) ans.push_back(a[n]), n--, m--;

        else if (dp[n][m-1] < dp[n-1][m]) n--;

        else m--;

    }

    for (int i = ans.size() - 1; i >= 0; i--)

        fout << ans[i] << ' ';

}