#include<bits/stdc++.h>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m;
int v[1025], v2[1025];
int sir[1025], bs;
int dp[1025][1025];
int main()
{
    fin >> n >> m;
    for(int i=1; i<=n; i++)
        fin >> v[i];
    for(int i=1; i<=m; i++)
        fin >> v2[i];
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
            if(v[i]==v2[j])
                dp[i][j]=dp[i-1][j-1]+1;
            else
                dp[i][j]=max(dp[i-1][j], dp[i][j-1]);
    for(int i=n, j=m; i;)
    {
        if(v[i]==v2[j]){
            bs++;
            sir[bs]=v[i];
            i--;
            j--;
        }
        else if(dp[i-1][j]<dp[i][j-1])
            j--;
        else
            i--;
    }
    fout << bs << "\n";
    for(int i=bs; i>=1; i--)
        fout << sir[i] << " ";
    return 0;
}