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

#define MAX 1025
int A[MAX], B[MAX];
int dp[MAX][MAX];

pair<int, int> best[MAX][MAX];

int main() {

    ifstream cin ("cmlsc.in");
    ofstream cout ("cmlsc.out");

    int N, M; cin >> N >> M;
    for (int i = 1; i <= N; i++) {
	cin >> A[i];
    }

    for (int i = 1; i <= M; i++) {
	cin >> B[i];
    }


    int ans = 0;
    pair<int, int> aa;
    for (int i = 1; i <= N; i++) {
	for (int k = 1; k <= M; k++) {
	    dp[i][k] = max (dp[i - 1][k], dp[i][k - 1]);
	    if (dp[i][k] < dp[i - 1][k]) {
		dp[i][k] = dp[i - 1][k];
		best[i][k] = best[i - 1][k];
	    }
	    if (dp[i][k] < dp[i][k - 1]) {
		dp[i][k] = dp[i][k - 1];
		best[i][k] = best[i][k - 1];
	    }
	    
	    if (A[i] == B[k]) {
		if (dp[i][k] < dp[i - 1][k - 1] + 1) {
		    dp[i][k] = dp[i - 1][k - 1] + 1;
		    best[i][k] = {i, k};
		}
	    }

	    if (dp[i][k] > ans) {
		ans = dp[i][k];
		aa = {i, k};
	    }
	}
    }

    cout << ans << "\n";
    int xx = aa.first;
    int yy = aa.second;

    vector<int> sol;
    while (xx >= 0 && yy >= 0 && dp[xx][yy] != 0) {
	if (A[xx] == B[yy]) {
	    sol.push_back(A[xx]);
	    --xx; --yy;
	}
	if (dp[xx - 1][yy] < dp[xx][yy - 1]) {
	    --yy;
	} else {
	    --xx;
	}
    }

    for (int i = sol.size() - 1; i >= 0; i--) {
	cout << sol[i] << " ";
    }
    cout << "\n";
    
    return 0;
}