#include <iostream>
#include <fstream>
using namespace std;
ofstream fout("cmlsc.out");
ifstream fin("cmlsc.in");
int n,m,s1[1050],s2[1050],dp[1050][1050],k,sp[1050];
int main()
{
    fin>>n>>m;
    for(int i=1; i<=n; i++)
        fin>>s1[i];
    for(int i=1; i<=m; i++)
        fin>>s2[i];
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
        {
            dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
            if(s1[i]==s2[j])
            {
                dp[i][j]=max(dp[i][j],dp[i-1][j-1]+1);
            }
        }
    fout<<dp[n][m]<<"\n";
    int i=n,j=m;
    while(dp[i][j]>0)
    {
        if(dp[i][j]>dp[i][j-1] && dp[i][j]>dp[i-1][j])
        {
            k++;
            sp[k]=s1[i];
            i--;
            j--;

        }
        else
        if(dp[i][j]>dp[i-1][j])
            j--;
        else
        if(dp[i][j]>dp[i][j-1])
            i--;
        else
            i--;
    }
    for(int i=k;i>=1;i--)
    {
        fout<<sp[i]<<" ";
    }
    return 0;
}