#include <bits/stdc++.h>
using namespace std;
const int MAXN = (1 << 10) + 3;
int a[MAXN], b[MAXN], dp[MAXN][MAXN], maxim ;
vector <int> ans;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int main(){
    int n, m; 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 = 0; i <= n; ++i){
        for(int j = 0; j <= m; ++j){
            if(i == 0 or j == 0) dp[i][j] = 0;
            dp[i + 1][j] = max(dp[i][j], dp[i + 1][j]);
            dp[i][j + 1] = max(dp[i][j], dp[i][j + 1]);
            dp[i + 1][j + 1] = dp[i][j] + (a[i + 1] == b[j + 1]);
        }
    }
    int i = n, j = m;
    fout << dp[n][m] << '\n';
    while(i and j){
        if(a[i] == b[j]) ans.push_back(j), i--, j--;
        else if(dp[i][j] == dp[i - 1][j]) i--;
        else if(dp[i][j] == dp[i][j - 1]) j--;
    }
    for(i = ans.size() - 1; i >= 0; --i) fout << b[ans[i]] << " " ;
    return 0;
}