C++ :

#include <iostream>
#include <queue>
using namespace std;
int main()
{
	priority_queue<int,vector<int>,greater<int> >q;
	int n,x,y,i,j;
	cin>>n;
	for(i=1;i<=n;i++)
	{
		cin>>x;
		for(j=1;j<=x;j++)
		{
			cin>>y;
			q.push(y);
		}
	}
	while(!q.empty()) 
	{
		cout<<q.top()<<endl;
		q.pop();
	}
	return 0;
}