#include <bits/stdc++.h>

using namespace std;

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

short n, m, v1[1025], v2[1025], dp[1025][1025];

int main()
{
    fin>>n>>m;
    for(int i = 1; i <= n; ++i)
        fin>>v1[i];
    for(int i = 1; i <= n; ++i)
        fin>>v2[i];

    for(int i = 1; i <= n; ++i)
    {
        for(int j = 1; j <= m; ++j)
        {
            if(v1[i] == v2[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;
    stack<int> s;

    while(i >= 1 && j >= 1)
    {
        if(v1[i] == v2[j])
        {
            s.push(v1[i]);
            --i; --j;
        }
        else if(dp[i-1][j] > dp[i][j-1])
            --i;
        else
            --j;
    }
    while(!s.empty())
    {
        fout<<s.top()<<" ";
        s.pop();
    }







    return 0;
}