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

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

void dp(){
    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 j=1;j<=m;j++)scanf("%d ",&b[j]);

    dp();
    printf("%d\n",c[n][m]);

    tipar( n,m );
    return 0;
}