#include <bits/stdc++.h>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m, dp[1050][1050];
int a[1050], b[1050], c[1050];
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]);
            }
        }
    }

    fout << dp[n][m] << '\n';

    int i, j, bst = 0;
    for (i=n, j=m; i>=1;){
        if (a[i] == b[j]){
            c[++bst] = a[i];
            i --;
            j --;
        }else if (dp[i-1][j] < dp[i][j-1]){
            j --;
        }else{
            i --;
        }
    }

    for (i=bst;i;i--){
        fout << c[i] << ' ';
    }
    fout << '\n';
    return 0;
}