#include <bits/stdc++.h>

using namespace std;
int n,m;
int main()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    cin>>n>>m;
    vector<int> a(n+1);
    vector<int> b(m+1);
    for(int i=1;i<=n;i++)cin>>a[i];
    for(int i=1;i<=m;i++)cin>>b[i];
    vector<vector<int>> dp(n+1,vector<int>(m+1,0));
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            if(a[i]==b[j]) dp[i][j]=dp[i-1][j-1]+1;
            else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
        }
    }
    cout<<dp[n][m]<<'\n';
    vector<int> sol;
    int i=n,j=m;
    while(i>0&&j>0)
    {
        if(a[i]==b[j])
        {
            sol.push_back(a[i]);
            i--;
            j--;
        }
        else
        if(dp[i-1][j]>=dp[i][j-1])i--;
        else
        j--;
    }
    reverse(sol.begin(),sol.end());
    for(int x:sol) cout<<x<<' ';
    return 0;
}