#include <bits/stdc++.h>
using namespace std;
int c[1050][1050],a[1050],b[1050],i,j,n,m,k,hx[1050];
int main(){
    ifstream cin("cmlsc.in");
    ofstream cout("cmlsc.out");
    cin>>n>>m;
    for (i=1;i<=n;i++)
    cin>>a[i];
    for (j=1;j<=m;j++)
    cin>>b[j];
    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]);
            } 
 cout<<c[n][m]<<'\n';
    i=n;
    j=m;
    while (c[i-1][j]!=0 && c[i][j-1]!=0){
        if (c[i][j]==c[i-1][j]) i--;
        else if (c[i][j]==c[i][j-1]) j--;
        else if (c[i][j]==1+c[i-1][j-1]) {
   hx[k]=a[i];
   k++;     
            i--;
            j--;
        }
         
    }
hx[k]=a[i];
    for (i=k;i>=0;i--)
    cout<<hx[i]<<" ";
  return 0;
}