#define DM 1025
#include <fstream>
#include <stack>
using namespace std;
 
ifstream cin ("cmlsc.in");
ofstream cout ("cmlsc.out");
int v1[DM], v2[DM], n, m, mx, mxl, dp[DM][DM], perf[DM];
stack <int> s;
 
int mxa(int a, int b)
{
    int ja = 0;
    for (int i = 1; i < b; ++i)
        if (dp[a][i] > dp[a][ja])
            ja = i;
    return ja;
}
 
int main() {
    cin >> n >> m;
    if (n >= m)
    {
        for (int i = 1; i <= n; ++i)
            cin >> v1[i];
        for (int j = 1; j <= m; ++j)
            cin >> v2[j];
    }
    else
    {
        for (int i = 1; i <= n; ++i)
            cin >> v2[i];
        for (int j = 1; j <= m; ++j)
            cin >> v1[j];
        swap(n, m);
    }
    for (int i = 1; i <= n; ++i)
    {
        mx = 0;
        for (int j = 1; j <= m; ++j)
        {
            if (v1[i] == v2[j])
                dp[i][j] = dp[i-1][mxa(i - 1, j)] + 1;
            else
                dp[i][j] = dp[i-1][j];
            if (dp[i][j] > dp[i][mx])
                mx = j;
        }
        perf[i] = mx;
        if (dp[n][mx] > dp[mxl][perf[mxl]])
            mxl = i;
    }
    s.push(v2[mx]);
    int a = mx;
    cout << dp[n][mx] << '\n';
    for (int i = mxl - 1; dp[n][mx] && i; --i)
        for (int j = a - 1; j >= 1; --j)
            if (dp[i][j] == dp[mxl][a] - 1 && v1[i] == v2[j])
            {
                s.push(v2[j]);
                a = j, --dp[n][mx], mxl = i;
                break;
            }
    while (!s.empty())
    {
        cout << s.top() << ' ';
        s.pop();
    }
    return 0;
}