#include <bits/stdc++.h>

using namespace std;

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

int n, m;
int a[1025];
int b[1025];

int dp[1025][1025];

int main() {

    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]);
        }
    }

    int i = n, j = m;
    vector<int> v;

    while(0 < i && 0 < j){
        if(a[i] == b[j]){
            v.push_back(a[i]);
            i--;
            j--;
        }
        else if(dp[i-1][j] >= dp[i][j-1])
            i--;
        else
            j--;

    }
    reverse(v.begin(), v.end());

    fout<<dp[n][m]<<"\n";
    for(int x : v)
        fout<<x<<" ";


    return 0;
}