#include<bits/stdc++.h>
using namespace std;

const int N = 1e5 + 10;
vector<int> v[N];

int main()
{
	int n, m;
	cin >> n >> m;
	while (m--)
	{
		int x, y;
		cin >> x >> y;
		v[x].push_back(y);
	}
	
	for (int i = 1; i <= n; i++)
	{
		cout << v[i].size() << " ";
		sort(v[i].begin(), v[i].end());
		for (int j = 0; j < v[i].size(); j++)
			cout << v[i][j] << " ";
		cout << endl;
	}
		
	
	return 0;
}