#include <iostream>
#include <fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
const int MAX = 1030;
int a[MAX],na,b[MAX],nb,dp[MAX][MAX],i,j,sol[MAX];
int main()
{
    in>>na>>nb;
    for(i = 1;i<=na;i++)
        in>>a[i];
    for(i = 1;i<=nb;i++)
        in>>b[i];
    for(i=1;i<=na;i++)
        for(j=1;j<=nb;j++)
            if(a[i]==b[j])
                dp[i][j] = 1+dp[i-1][j-1];
            else
                dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
    int x = na,y = nb;
    while(dp[x][y]>0)
    {
        if(a[x]==b[y])
        {
            sol[dp[x][y]] = a[x];
            --x;--y;
        }
        else if(dp[x][y]==dp[x-1][y])
            x--;
        else
            y--;
    }
    out<<dp[na][nb]<<'\n';
    for(i=1;i<=dp[na][nb];i++)
        out<<sol[i]<<" ";
    return 0;
}