#include<cstdio>
#include<vector>
#include<iostream>
#define max(a,b) a > b ? a : b
using namespace std;
 
int n, m;
vector <int> a, b;
vector <vector <int> > lng; 
void AfiseazaSol(int x, int y){

    if (lng[x][y] == 0) return;
    int i, j;
     
    for (j = y; j >= 1 && lng[x][j] == lng[x][j-1]; j--);
    for (i = x; i >= 1 && lng[i][j] == lng[i-1][j]; i--);     
    AfiseazaSol(i - 1, j - 1);
    printf("%d ", a[i]);
} 
int main(){
    freopen("cmlsc.in", "r", stdin), freopen("cmlsc.out", "w", stdout);
    scanf("%d %d", &n, &m);
   int i, j;
    a.assign(n + 1, 0);
    b.assign(m + 1, 0);
    lng.resize(n + 1);
    for (i = 0; i <= n; i++) lng[i].resize(m + 1);
     
    for (i = 1; i <= n; i++) scanf("%d", &a[i]);
    for (i = 1; i <= m; i++) scanf("%d", &b[i]);
    
    for (i = 0; i <= n; i++)
        for (j = 0; j <= m; j++) lng [i][j] = 0;
     
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
           if (a[i] == b[j]) lng[i][j] = lng[i-1][j-1] + 1;
           else lng[i][j] = max (lng[i-1][j], lng[i][j-1]);
     
    printf("%d\n", lng[n][m]);
    AfiseazaSol(n, m);
    return 0;
}