#include <bits/stdc++.h>
using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
#define cin f
#define cout g
int dp[1035][1035],i,j,n,m,a[1035],b[1035];
signed main()
{
    cin>>n>>m;
    for(i=1;i<=n;i++){
        cin>>a[i];
    }
    for(i=1;i<=m;i++){
        cin>>b[i];
    }
    for(i=1;i<=n;i++){
        for(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> sir;
    i=n; j=m;
    while(i>0 && j>0){
        if(a[i]==b[j]){
            sir.push_back(a[i]);
            i--;
            j--;
        }
        else if(dp[i-1][j]>=dp[i][j-1]){
            i--;
        }
        else{
            j--;
        }
    }
    reverse(sir.begin(),sir.end());
    for(auto p:sir){
        cout<<p<<" ";
    }
    return 0;
}