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

struct loc{
    vector<int> num;
};

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