#include <fstream>
using namespace std;
ifstream fin ("interclasari.in");
ofstream fout ("interclasari.out");
int n,m,i,j,c,l,nr,e,a[1000],b[1000],s[1000],d,k,sol[1000],sum;
int main (){
    fin>>nr;
    fin>>m;
    d=1;
    sum=m;
    for(i=1;i<=m;i++){
        fin>>a[i];
    }
    for(e=2;e<=nr;e++){
        fin>>n;
        for(j=1;j<=n;j++)
            fin>>b[j];
        i=1;
        j=1;
        c=0;
        while(i<=m && j<=n){
            if(a[i]>b[j]){
                c++;
                s[c]=b[j];
                j++;

            } else {
                c++;
                s[c]=a[i];
                i++;

            }
        }

        for(;i<=m;i++){
            c++;
            s[c]=a[i];

        }
        for(;j<=n;j++){
            c++;
            s[c]=a[j];
        }
        for (i=1;i<=c;i++)
            a[i] = s[i];

        m = c;
    }
    fout<<c<<"\n";

    for(i=1;i<=c;i++)
        fout<<a[i]<<" ";


    return 0;
}