#include <bits/stdc++.h>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int n,m,a[1026],b[1026],dp[1026][1026],sol[1026];

int main()
{
    int i,j;
    fin>>n>>m;
    for(i=1;i<=n;i++)
        fin>>a[i];

    for(j=1;j<=m;j++)
        fin>>b[j];

    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            if(a[i]==b[j])dp[i][j]=1+dp[i-1][j-1];
            else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);

    fout<<dp[n][m]<<"\n";

    int k=0;
    for(i=n,j=m;i;)
        if(a[i]==b[j])
        {
            sol[++k]=a[i];
            i--;
            j--;
        }
        else if(dp[i-1][j]<dp[i][j-1])j--;
        else i--;

    for(i=k;i>=1;i--)
        fout<<sol[i]<<" ";
    return 0;
}