#include <fstream>
#include <cmath>
#define nmax 1025
using namespace std;

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

int x[nmax], y[nmax], l[nmax][nmax];
int n,m;

void Citire()
{int i;
 fin>>n>>m;
 for(i=1; i<=n;i++) fin>>x[i];
 for(i=1; i<=m;i++) fin>>y[i];
}

void LCS()
{int i,j;
for(i=1;i<=n;i++)
    for(j=1;j<=n;j++)
        if(x[i]==y[i])
            l[i][j]=1+l[i-1][j-1];
        else
            l[i][j]=max(l[i][j-1],l[i-1][j]);
}

void Afisare()
{int d[nmax],k=0,i,j;
fout<<l[n][m]<<"\n";
i=n; j=m;
while(j>0&&i>0)
    {if(x[i]==y[j])
        {d[++k]=x[i];
        i--;
        j--;
        }
    else
        if(l[i][j-1]>l[i-1][j])
            j--;
        else
            i--;
    }
for(i=k;i>=1;i--)
    fout<<d[i]<<" ";
 }

int main()
{Citire();
 LCS();
 Afisare();
 fin.close();
 fout.close();
 return 0;
}