#include<bits/stdc++.h>
using namespace std;
#define in f
#define out g
#define maxx 1030

ifstream f("cmlsc.in");
ofstream g("cmlsc.out");

int n;
int m;
int v1[maxx];
int v2[maxx];
int solution[maxx];
int M[maxx][maxx];
int h;

int main() {

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

    for(int i = 1; i <= n; ++i) {
        for(int j = 1; j <= m; ++j) {
            if(v1[i] == v2[j]) {
                M[i][j] = M[i - 1][j - 1] + 1;
            } else {
                M[i][j] = max(M[i][j - 1], M[i - 1][j]);
            }
        }
    }
    out << M[n][m] << endl;
    for(int i = n; i >= 1; --i) {
        for(int j = m; j >= 1; --j) {
            if(v1[i] == v2[j]) {
                solution[h++] = v1[i];
                i--;
                j--;
            } else {
                if(M[i][j - 1] > M[i - 1][j]) {
                    j--;
                } else {
                    i--;
                }
            }
        }
    }
    for(int i = h - 1; i >= 0; --i) {
        out << solution[i] << " ";
    }
}