#include <fstream>
#define DIM 1300
using namespace std;
ifstream fin ("cmlsc.in" );
ofstream fout("cmlsc.out");
int D[DIM][DIM], i, j, A[DIM], B[DIM], C[DIM], N, M;
void SetUp(){
fin >> N >> M;
for(i = 1; i <= N; i ++)
fin >> A[i];
for(j = 1; j <= M; j ++)
fin >> B[j];
return;
}
int MAX(int a, int b){
if(a >= b) return a;
if(a <= b) return b;
}
void Dinamic(){
for(i = 1; i <= N; i ++)
for(j = 1; j <= M; j ++){
if(A[i] == B[j])
D[i][j] = D[i-1][j-1] + 1;
else
D[i][j] = MAX(D[i-1][j], D[i][j-1]);
}
return;
}
void Rebuild(){
fout << D[N][M] << "\n";
i = N; j = M;
while(i != 0 && j != 0){
if(A[i] == B[j]){
C[D[i][j]] = A[i];
i --;
j --;
}
else{
if(D[i-1][j] == D[i][j])
i --;
else
if(D[i][j-1] == D[i][j])
j --;
}
}
for(i = 1; i <= D[N][M]; i ++)
fout << C[i] << " ";
return;
}
int main(){
SetUp();
Dinamic();
Rebuild();
return 0;
}