#include<stdio.h>
int n,i,m,v[1000001],k,j,l,r,a[5000001],b[5000001],t;
int main() {
    freopen("interclasari.in","r",stdin),freopen("interclasari.out","w",stdout),scanf("%d",&n);
    while(n--) {
        scanf("%d",&m);
        for(j=1;j<=m;j++)
            scanf("%d",v+j);
        for(t=0,j=l=1;j<=k&&l<=m;)
            b[++t]=a[j]>v[l]?v[l++]:a[j++];
        for(;j<=k;b[++t]=a[j++]);
        for(;l<=m;b[++t]=v[l++]);
        for(k+=m,j=1;j<=k;j++)
            a[j]=b[j];
    }
    printf("%d\n",k);
    for(i=1;i<=k;i++)
        printf("%d ",a[i]);
}