#include <bits/stdc++.h>
using namespace std;
int m, n, i, j, k;
int a[1035], b[1035], lcs[2070], dp[1035][1035];
int main()
{
    ifstream f("cmlsc.in");
    ofstream g("cmlsc.out");
    f >> m >> n;
    for(i = 1; i <= m; i ++)
        f >> a[i];
    for(i = 1; i <= n; i ++)
        f >> b[i];
    if(a[1] == b[1]) dp[1][1] = 1;
                else dp[1][1] = 0;
    for(i = 2; i <= m; i ++)
        if(b[1] == a[i]) dp[1][i] = 1;
                    else dp[1][i] = dp[1][i - 1];
    for(i = 2; i <= n; i ++)
        if(a[1] == b[i]) dp[i][1] = 1;
                    else dp[i][1] = dp[i - 1][1];
    for(i = 2; i <= n; i ++)
     {
        for(j = 2; j <= m; j ++)
        {
            if(b[i] == a[j])dp[i][j] = dp[i - 1][j - 1] + 1;
            else dp[i][j]=max(dp[i - 1][j], dp[i][j - 1]);
        }
     }
    i = n;
    j = m;
    while(i != 0)
    {
        if(b[i] == a[j])
        {
            lcs[++k] = a[j];
            i--;
            j--;
        }
        else if(dp[i][j - 1] >= dp[i - 1][j])j--;
        else i--;
    }
    g << dp[n][m] << "\n";
    for(i = dp[n][m]; i >= 1; i --)
        g << lcs[i] << " ";
    return 0;
}