#include <fstream>
using namespace std;
ifstream cin("cmlsc.in"); ofstream cout("cmlsc.out");
int n,m,a[1000],b[1000],i,j,rez[1000],rezl,nr,c[1000][1000];
int main()
{ cin>>n>>m; 
	for(i=1;i<=n;i++) cin>>a[i];
    for(i=1;i<=m; i++) cin >> b[i];
    for(i=1;i<=n;i++) { for(j = 1; j <= m; j++) if(a[i] == b[j]) c[i][j] = c[i-1][j-1]+1;else c[i][j] = max(c[i-1][j], c[i][j-1]);}
    i = n;j = m;
    while(i && j)
    {
        if(a[i] == b[j])
        {
            rezl++;
            rez[rezl] = a[i];
            i--;
            j--;
        }
        else
        {
            if(c[i-1][j] > c[i][j-1])
                 i--;
            else j--;
        }
    }
    cout << c[n][m] << '\n';
    for(i=rezl; i >= 1; i--)
        cout << rez[i] << ' ';
    return 0;
}