#include<cstdio>
#include<vector>
using namespace std;
vector <int> v[25];
vector <int> vec;
int ind[25],s,k,minn;
void interclasari(){
    for(int i=0;i<s;i++){
        int h=-1;
        minn=(1<<30);
        for(int j=0;j<k;j++)
            if(ind[j]<(int)v[j].size() && v[j][ind[j]]<minn){
                minn=v[j][ind[j]];
                h=j;
            }
        vec.push_back(minn);
        ind[h]++;
    }
}
int main(){
    freopen("interclasari.in","r",stdin);
    freopen("interclasari.out","w",stdout);
    int n;
    scanf("%d", &k);
    for(int i=0;i<k;i++){
        scanf("%d", &n);
        s+=n;
        v[i].resize(n);
        for(int j=0;j<n;j++)
            scanf("%d", &v[i][j]);
    }
    interclasari();
    printf("%d\n", s);
    for(int i=0;i<s;i++)
        printf("%d ", vec[i]);
    return 0;
}