#include <bits/stdc++.h>

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m, a[1030], b[1030], cnt = 0, v[1030], dp[1030][1030];

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]) dp[i][j] = dp[i-1][j-1] + 1;
            else dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
        }
    }
    int i = n, j = m;
    while(i != 0 && j != 0) {
        if(a[i] == b[j]) v[++cnt] = a[i], i--, j--;
        else if(dp[i-1][j] < dp[i][j-1]) j--;
        else i--;
    }
    fout << cnt << '\n';
    for(int i=cnt; i>=1; i--) fout << v[i] << " ";

    return 0;
}