#include <cstdio>
#include <algorithm>
#include <vector>
 
using namespace std;
 
const int MAX = (1 << 10) + 5;
 
int n, m;
int a[MAX], b[MAX], dp[MAX][MAX];
vector<int> v;
 
int main() {
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
     
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
        scanf("%d", &a[i]);
    for (int i = 1; i <= m; i++) 
        scanf("%d", &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]);
 
    printf("%d\n", dp[n][m]);
     
    int i = n, j = m, sol = dp[n][m];
    while (i >= 1 && j >= 1 && sol) 
        if (a[i] == b[j]) {
            v.push_back(a[i]);
            i--, j--, sol--;
        } else {
            if (dp[i][j] == dp[i - 1][j])
                i--;
            else j--;
        }
     
    while (!v.empty()) {
        printf("%d ", v.back());
        v.pop_back();
    }
     
 
    return 0;   
}