#include <fstream>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <climits>

#include <ctype.h>


using namespace std;


//ifstream f("in.in");
//ofstream g("out.out");

ifstream f("interclasari.in");
ofstream g("interclasari.out");

int n,m,kk,a[1000005],b[1000005],c[20000005];

int main(){

    f>>kk;
    f>>n;
    for(int i=1;i<=n;i++){
        f>>a[i];
    }

    for(int l=2;l<=kk;l++){
        f>>m;
        for(int ll=1;ll<=m;ll++){
            f>>b[ll];
        }

        int i=1,j=1,k=0;
        while(i<=n&&j<=m){
            k++;
            if(a[i]<b[j]){
                c[k] = a[i];
                i++;
            }else{
                c[k] = b[j];
                j++;
            }
        }
        for(;i<=n;i++){
            k++;
            c[k] = a[i];
        }
        for(;j<=m;j++){
            k++;
            c[k] = b[j];
        }

        for(int ll=1;ll<=k;ll++){
            a[ll] = c[ll];
        }
        n=k;
    }

    g<<n<<'\n';
    for(int i=1;i<=n;i++){
        g<<a[i]<<" ";
    }


    f.close();
    g.close();
    return 0;
}