#include <iostream>
#include <fstream>
using namespace std;
ifstream fin ("cmlsc.in");
ofstream fout ("cmlsc.out");
unsigned a[1525][1525];
int main()
{
    unsigned v1[1525],v2[1525],v3[1525],m,n,k=0;
    fin>>m>>n;
    for(unsigned i=1;i<=m;i++)fin>>v1[i];
    for(unsigned i=1;i<=n;i++)fin>>v2[i];
    /*
    if(v1[m]==v2[n]){
    a[n][m]=1;
    v3[++k]=v1[m];}
    for(unsigned i=m-1;i>=1;i--)
        if(v1[i]==v2[n]){a[n][i]=a[n][i+1]+1;v3[++k]=v2[n];}
        else
        a[n][i]=a[n][i+1];
    for(unsigned i=n-1;i>=1;i--)
        if(v2[i]==v1[m]){a[i][m]=1+a[i+1][m];v3[++k]=v1[m];}
        else
        a[i][m]=a[i+1][m];
*/
    for(int i=n;i>=1;i--)
        for(int j=m;j>=1;j--)
            if(v1[j]==v2[i])a[i][j]=1+a[i+1][j+1];
            else {
                if(a[i+1][j]>a[i][j+1])a[i][j]=a[i+1][j];
                else a[i][j]=a[i][j+1];
            }
    /*for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++)
            cout<<a[i][j]<<' ';
        cout<<'\n';
    }*/
    fout<<a[1][1]<<'\n';
    int i,j;
    for (i = n, j = m; i; )
        if (v2[i] == v1[j])
            v3[++k] = v2[i], --i, --j;
        else if (a[i-1][j] < a[i][j-1])
            --j;
        else
            --i;
    for(int i=k;i>=1;i--)fout<<v3[i]<<' ';
}