#include <iostream>
#include <fstream>
using namespace std;

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

int dp[1030][1030];
int a[1030], b[1030];
int ans[1030];

int main()
{
    int n, m; 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";
    int k = dp[n][m];
    int i = n, j = m;
    while(i != 1 && j != 1) {
        while(dp[i-1][j-1] == k)
            i--, j--;
        ans[k] = a[i];
        k--;
        if(dp[i-1][j] == k)
            i--;
        else
            j--;
    }
    for(int i = 1; i <= dp[n][m]; ++i)
        fout << ans[i] << " ";
}