#include <fstream>

using namespace std;

#define SIZE 1025

short a[SIZE];
short b[SIZE];
short sir[SIZE];
short mat[SIZE][SIZE];

int main(){
int i,j,k;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
int m,n;

in>>m>>n;

for(i=1;i<=m;i++){
in>>a[i];
mat[i][0] = 0;
}
for(i=1;i<=n;i++){
in>>b[i];
mat[0][i]=0;
}
mat[0][0]=0;
for(i=1;i<=m;i++)
for(j=1;j<=n;j++)
if(a[i]==b[j])
mat[i][j] = mat[i-1][j-1]+1;
else
if(mat[i-1][j]>mat[i][j-1])
mat[i][j] = mat[i-1][j];
else
mat[i][j] = mat[i][j-1];
i=m;j=n;k=0;
while(i&&j){
if(a[i] == b[j]){
sir[k++] = a[i];
i--;
j--;
}
else
if(mat[i-1][j]>mat[i][j-1])
i--;
else
j--;
}
out<<k<<endl;
for(i=k-1;i>=0;i--)
out<<sir[i]<<" ";
out<<endl;
return 0;
}