#include <fstream>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int n,m,i,j,a[1030],b[1030],dp[1030][1030],ans[1030],nr;

int main()
{
    fin >> n >> m;
    for (i=1; i<=n; i++)
        fin >> a[i];
    for (i=1; i<=m; i++)
        fin >> b[i];
    for (i=1; i<=n; i++)
        for (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]);
    fout << dp[n][m] << '\n';
    i=n;
    j=m;
    while (i&&j)
        if (a[i]==b[j])
        ans[++nr]=a[i],i--,j--;
    else
        if (dp[i-1][j]>dp[i][j-1])
        i--;
    else
        j--;
    for (i=nr; i; i--)
        fout << ans[i] << ' ';
    fout << '\n';
}