#include <fstream>

using namespace std;

ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

int dp[1025][1025];
int a[1025];
int b[1025];

void sirul(int l, int c){
    if(l == 0 || c == 0){
        return;
    }
    if(a[l] == b[c]){
        sirul(l-1,c-1);
        out<<a[l]<<' ';;
    } else if(dp[l-1][c] > dp[l][c-1]) {
        sirul(l-1,c);
    } else {
        sirul(l,c-1);
    }
}

int main() {
    int m, n;
    in >> m >> n;

    for (int i = 1; i <= m; i++) {
        in >> a[i];;
    }

    for (int i = 1; i <= n; i++) {
        in >> b[i];
    }

    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            if (a[i] == b[j]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            } else {
                dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
            }
        }
    }

    out << dp[m][n] << "\n";
    sirul(m,n);

    return 0;
}