#include <bits/stdc++.h>

using namespace std;
const int NMAX=1e3 + 50;
int a[NMAX],b[NMAX],n,m,dp[NMAX][NMAX],v[NMAX];
int main()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%d %d", &n, &m);
int k=0;
    for (int i = 1; i <= n; ++i)
        scanf("%d ", &a[i]);
    for (int i = 1; i <= m; ++i)
        scanf("%d ", &b[i]);
    for (int i = 1; i <= n; ++i)
        dp[i][0]=0;
    for (int j = 1; j <= m; ++j)
        dp[0][j]=0;
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j)


            if (a[i]==b[j]) dp[i][j]=dp[i-1][j-1]+1,v[++k]=a[i];
            else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
    printf("%d", dp[n][m]);
    printf("\n");
    for (int i = 1; i <= dp[n][m]; ++i)
        printf("%d ",v[i]);
    return 0;
}