#include <fstream>

using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
int b[1025], c[1025], m, n, i, j,x=0, a[1025][1025], sub[1025];
int main()
{
    f >> n >> m;
    for( i = 1; i<=n ; i++)
        f >> b[i];
    for( i = 1 ; i <=m ; i++ )
        f >> c[i];
        for(i=1; i<=n; i++)
            for(j=1; j<=m; j++)
        {
            if(b[i]==c[j])
            a[i][j]=a[i-1][j-1]+1;
            else
            a[i][j]=max(a[i-1][j],a[i][j-1]);
        }
    i=n; j=m;
    while(a[i][j])
    {
        while(a[i][j]==a[i-1][j])
            i--;
        while(a[i][j]==a[i][j-1])
            j--;

            x++;
            sub[x]=b[i];

            i--;
             j--;
    }
    g<<a[n][m]<<"\n";
    for(i=x; i>=1; i--)
        g<<sub[i]<<" ";
return 0;
}