#include <bits/stdc++.h>
using namespace std;

const string file_name = "cmlsc";
ifstream fin(file_name + ".in");
ofstream fout(file_name + ".out");

int n, m, v[1030], v2[1030], mat[1040][1040];

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

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

    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(v[i] == v2[j])
                mat[i][j] = 1 + mat[i-1][j-1];
            else
                mat[i][j] = max(mat[i-1][j], mat[i][j-1]);
        }
    }

    int k = mat[n][m];
    string arr;

    fout << mat[n][m] << "\n";

    int i = n, j = m;
    while(i != 0 && j != 0){
        if(v[i] == v2[j])
            arr += to_string(v[i]), i--, j--;
        else if(mat[i-1][j] < mat[i][j-1])
            j--;
        else
            i--;

    }

    for(int i = arr.size() - 1; i >= 0; i--)
        fout << arr[i] << " ";


    return 0;
}