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#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1026],b[1026],n,m,dp[1026][1026];
int main()
{
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        fin>>a[i];
    }
    for(int j=1;j<=m;j++)
    {
        fin>>b[j];
    }
    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]);}
        }
    }
    fout<<dp[n][m]<<'\n';
    for(int i=1;i<=n;i++)
    {
        if(dp[i][m]>dp[i-1][m]){fout<<a[i]<<" ";}
    }
    fin.close();
    fout.close();
    return 0;
}