#include <iostream>
#include <fstream>

using namespace std;

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

int n, m;
int a[1050], b[1050], d[1050][1050];

void drum(int i, int j, int k) {
    if (k!=0) {
        if (a[i] == b[j]){
            drum(i-1, j-1, k-1);
            fout<<a[i]<<" ";
        }else
            if (d[i-1][j] > d[i][j-1])
                drum(i-1, j, k);
            else
                drum(i, j-1, k);
    }
}

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])
                d[i][j] = d[i-1][j-1] + 1;
            else
                d[i][j] = max(d[i-1][j], d[i][j-1]);

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

    drum(n, m, d[n][m]);
}