#include <iostream>
#include <fstream>

using namespace std;
ifstream fi("cmlsc.in");
ofstream fo("cmlsc.out");
short int m(short int a,short int b)
{
    if (a<b) return a;
    return b;
}
void read(short int v[],short int x)
{
    for (int i=0;i<x;i++)
    {
        fi>>v[i];
    }
}
int main()
{
    short int M,N;
    fi>>M>>N;
    short int A[M],B[N],v[m(M,N)],i,j,k=0,y;
    read(A,M);
    read(B,N);
    for (i=0;i<M;i++)
    {
        for (j=y;j<N;j++)
            if (A[i]==B[j])
            {
                v[k]=A[i];
                k++;
                y=j;
            }
    }
    fo<<k<<"\n";
    for (i=0;i<k;i++)
    {
        fo<<v[i]<<" ";
    }
    return 0;
}