#include <cstdio>
#include <algorithm>
using namespace std;
#define nmax 2000005
int S[nmax];
int main(void)
{
    freopen("interclasari.in","r",stdin);
    freopen("interclasari.out","w",stdout);
    int n,k,N=0,x;
    for (scanf("%d\n",&k);k;--k)
        {scanf("%d\n",&n);for (int i=1;i<=n;scanf("%d",&x),S[++N]=x,++i);}
    sort(S+1,S+N+1);
    printf("%d\n",N);
    for (int i=1;i<=N;printf("%d ",S[i]),++i);
    fclose(stdout);
}