#include<fstream>
using namespace std;
ifstream fin ("interclasari.in");
ofstream fout ("interclasari.out");
int k,i,j,x,y,m,vm,n,a[1000001],b[5000001],v[5000001];
int main () {

    fin>>k;
    for (i=1;i<=k;i++) {
        fin>>n;
        for (j=1;j<=n;j++)
            fin>>a[j];
        m=1;
        for (x=1,y=1;x<=n&&y<=vm;)
            if (a[x]<=v[y])
                b[m++]=a[x++];
            else
                b[m++]=v[y++];
        for (;x<=n;x++)
            b[m++]=a[x];
        for (;y<=vm;y++)
            b[m++]=v[y];
        vm+=n;
        for (j=1;j<=vm;j++)
            v[j]=b[j];
    }
    fout<<vm<<"\n";
    for (i=1;i<=vm;i++)
        fout<<v[i]<<" ";
    fout<<"\n";
    return 0;
}