#include<stdio.h>
int a[1025],b[1025],d[1025][1025];
int maxim ( int a , int b){
    if(a>b)
        return a;
    return b;
}
int main(){
    int n,m,i,j;
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(i=1;i<=n;i++)
        scanf("%d",&a[i]);
    for(i=1;i<=m;i++)
        scanf("%d",&b[i]);
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            if(a[i]==b[j])
                d[i][j]=1+d[i-1][j-1];
            else
                d[i][j]=maxim(d[i-1][j],d[i][j-1]);
    printf("%d\n",d[n][m]);
    int x=1;
    for(i=1;i<=n;i++){
        for(j=1;j<=m;j++)
            if(d[i][j]==x){
                printf("%d ",a[i]);
                x++;
            }
    }
    return 0;
}