#include <cstdio>
#include <algorithm>
using namespace std;
#define MAX 1025

int n,m,a[MAX],b[MAX],c[MAX][MAX];

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

void tipar(int n,int m){
    if(c[n][m] > 0)
    {
        if(a[n] == b[m])
        {
            tipar(n-1,m-1);
            printf("%d ",a[n]);
        } else
        if(c[n-1][m] > c[n][m-1])tipar(n-1,m); else tipar(n,m-1);
    }
}

int main(){
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
        scanf("%d %d",&n,&m);
        for(int i=1;i<=n;i++)scanf("%d",&a[i]);
        for(int i=1;i<=m;i++)scanf("%d",&b[i]);
    cmlsc();
        printf("%d\n",c[n][m]);
        tipar(n,m);
    return 0;
}