#include <bits/stdc++.h>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m;
int a[1030], b[1030], v[1030];
int dp[1030][1030];
int main()
{
    fin >> n >> m;
    for(int i = 1; i <= n; i ++)
        fin >> a[i];
    
    for(int j = 1; j <= m; j ++)
        fin >>b[j];

    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 i = n, j = m, cnt = 0;
    while(i && j)
    {
        if(a[i] == b[j])
        {
            v[++cnt] = a[i];
            i --;
            j --;
        }
        else if(dp[i - 1][j] < dp[i][j - 1])
            j --;
        else
            i --;
    }
    for(int i = cnt; i >= 1; i --)
        fout << v[i] << " "; 
    return 0;
}