#include<iostream>
using namespace std;
int a[1000001]={};
int c[1000001]={};
int main()
{
	int i,n,m,p,b,x,j,count=0;
	cin>>n>>m>>p;
	for (i=1;i<=n;i++)
	{
		cin>>b;
		for (j=1;j<=b;j++)
		{
			cin>>x;
			a[x]++;
		}		
	}
	for (i=1;i<=1000001;i++)
	{
		if (a[i]==p)
		{
			count++;
			c[count]=i;
		}	
	}
	cout<<count<<endl;
	for (i=1;i<=count-1;i++)
		cout<<c[i]<<" ";
	cout<<c[count];	
	return 0;
}