#include 
#include 
#include 
using namespace std;
const int maxn = 1e5 + 10;

vector graph[maxn];
int main() {
    int num_of_vertices;
    cin >> num_of_vertices;
    
    int num_of_edges;
    cin >> num_of_edges;
    
    
    for(int i = 0; i < num_of_edges; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b); // one directioanl
        graph[b].push_back(a); // two directioanal
    }
    
    for(int i = 0; i < num_of_vertices; i++) {
        cout << i << " --> ";
        for(int j = 0; j < (int) graph[i].size(); j++) {
            cout << graph[i][j] << ", ";
        }
        cout << endl;
    }
   
    

    return 0;
}