#include <fstream>
using namespace std;
ifstream cin("cmlsc.in");
ofstream cout("cmlsc.out");
int mat[1050][1050];
int A[1030],B[1030];
int sir[1050];
int main(){
    int a,b,c=0;
    cin >> a >> b;

    for(int i = 1; i <= a; i++){
    	cin >> A[i];
    }
    for(int i = 1; i <= b; i++){
    	cin >> B[i];
    }
    for(int i = 1; i <= a; i++){
    	for(int j = 1; j <= b; j++){
    		if(A[i]==B[j]){
    			mat[i][j] = mat[i-1][j-1]+1;
    		}else{ 
    		mat[i][j] = max(mat[i-1][j], mat[i][j-1]);
    	}
    		
    	}
    }

   int i = a;
    int j = b;
    while(i and j){
    	if(A[i] == B[j]){
    		c++;
    		sir[c] = A[i];//sau cu b[i] deoarece sunt =
    		i--;
    		j--;
    	}else if(mat[i-1][j]<mat[i][j-1]){
    		j--;
    	}else{
    		i--;
    	}
    }
cout << mat[a][b] << endl;
for(int  i = c; i >= 1; i--){
    cout <<  sir[i] << " ";
}


	return 0;
}